[Video Tutorial] Black Mesa Speedrun Guide (2021)

https://www.youtube.com/playlist?list=PL0WAeJTbS25k_h_sMUHchf9kfuT82oqQn

Getting started

This guide will help you with setting up the game and LiveSplit to get started speedrunning Black Mesa. Individual tricks and strategies are described in other **[Guides](https://www.speedrun.com/bms/guides)** found on this website.

# Choosing a version

There are multiple versions of Black Mesa to speedrun:

- **MOD** - Original version of Black Mesa released in 2012 as a Source mod. This version is free and features bunnyhopping and wallclimbing, however propclips are harder to perform and the gravity is set higher than in other versions. It also has the worst load times and often crashes.
You can download it from **[here](https://www.moddb.com/mods/black-mesa/downloads)**.

- **xengine** - Mostly obsolete version. It has the most skips but lacks reasonable bunnyhopping. It's the last version without Xen. 
Can be downpatched to within Steam's **Black Mesa properties** → **Betas** → select "**xengine(cu5) - xengine(cu5)**". Your current Black Mesa installation will be replaced with this version.

- **0.9** - Sometimes also referred to as 0.9.1 or 0.91. This is the preferred version when it comes to speedrunning. It has all the levels, including Xen, and features tricks like bunnyhopping and sliding, however it can sometimes crash.
This version can also be obtained through Steam directly. Right click Black Mesa in your game library, click on **Properties...** → **Betas** and select "**zero-point-nine - Xen 0.9**". This will replace your current game installation with version 0.9.

- **Current Version** - The current version of Black Mesa is similar to 0.9 in terms of movement, but with several disadvantages, especially when it comes to level design. 1.5 features reworked chapters, more puzzles, patched skips, improved (read harder to abuse) AI and explosive boosts do more self-damage. It is prettier but can be more demanding on your hardware.

# Setting up LiveSplit

LiveSplit is a timer program for speedrunners that is both easy to use and full of features. Thanks to its support for plugins, we can have the timer can automatically split, pause during game loading and stop when the run ends.

Download the current version from **[LiveSplits website](https://livesplit.org/)**. Next, download the latest version of SourceSplit from **[here](https://github.com/thisis2838/SourceSplit/releases)** to *<LiveSplit's installation folder> → Components*. Then go to LiveSplit's splits editor and make sure it is activated.

https://i.imgur.com/AVCNgFX.png
*This is what it should say.*

Now grab some premade splits from the **[Resources](https://www.speedrun.com/bms/resources)** tab. Make sure you are using the Subsplits option within the Layout Editor, otherwise the formatting will be messed up.

https://i.imgur.com/nqdzReG.png

Finally, make sure that you're comparing against game time.

https://i.imgur.com/a4onioF.png

# Setting up the game

## Launch Options

First of all, Launch Options. Right click Black Mesa in your Steam library and click **Properties...** and type *-oldgameui -console* into the **Launch Options** text box. This will force the game to use an older menu interface, which is less graphically demanding and also faster to navigate. Using the *-console* parameter launches the game with console already open. In addition, the game will launch much faster because it doesn't have to load animated backgrounds.

https://i.imgur.com/AzHVLSD.png

Another way to set launch options is through Windows shotrcuts. This is useful if don't want to launch the game through Steam.
Navigate to your Black Mesa root directory, right click **bms.exe** and click **Create shortcut**. Now right click the shortcut and open **Properties**. Type *-oldgameui -console* at the end of the **Target** text box, like this:

https://i.imgur.com/HeywoMH.png

## In-game settings

*Note: Some of the settings in this section only apply to retail versions, meaning you won't find them available on MOD.*

Launch the game. Go to **Options** → **Keyboard** → **Advanced...** → **Enable developer console**. While you're in the settings, go to the Black Mesa tab and tick **Enable Always Run**, **Enable Auto-Aim** and **Enable Auto Crouch-Jump**.

https://i.imgur.com/u5kjKsF.png

Always run not only lets you sprint without having to hold SHIFT, it also doubles crouching movement speed, making sliding, bunnyhopping and crawling through vents much more efficient. You also swim faster.
Auto Crouch-Jump lets you climb obstacles much faster. A good example of this is **[Residue Processing intro skip](https://youtu.be/ef-lOTO6E9U?t=14)**, which would be slower without the use of automatic crouch jumping. Furthermore, enabling this option will result in more speed gain with unpause boosts while taking the same amount of damage. It is necessary for boosts like **[this one in Unforseen Consequences](https://youtu.be/reoP7iz_PCI)**.

https://i.imgur.com/246TrCG.png
*UC Bridge skip with Auto Crouch-Jump on vs off*

Now go to **Video** → **Advanced...** options and try tinkering with the settings. Some features, especially dynamic lighting and shadows, are very resource intensive, making the framerate plummet in certain scenarios. Don't be afraid to turn some of the settings down. Keeping your framerates stable is much more important than having the game look slightly better.
Also, don't forget to turn the **Field of view** slider all the way up to 90.
It is recommended to use **Borderless Fullscreen** display mode instead of **Fullscreen**. This setting allows LiveSplit to be visible while in-game and it also speeds up alt-tabbing significantly, although it can have a slight impact on your performance.

## Key bindings

Open the developer console by pressing the **~** key. It is located above the **Tab** key on your keyboard. We are going to be binding keys to certain actions. This is vital to performing some of the tricks during runs efficiently.

- Type *bind mwheelup +jump* and *bind mwheeldown +jump*. These commands will bind your scroll wheel to jumping. This is important for bunnyhopping.

- Next, type *bind "key" "save quick; load quick"*. Replace the "key" with any key of your choice. List of key names can be found **[here](https://wiki.teamfortress.com/wiki/Scripting#List_of_key_names)**. Pressing the "key" will make a quicksave and load that quicksave immediately, which is useful in performing **[Save Deletion](https://wiki.sourceruns.org/wiki/Save_Deletion)** and **[Save/Load buffering](https://www.speedrun.com/bms/guide/qjt0l)**.

- It is recommended to bind a key for making a hard save. This save can be used when attempting tricks that require quicksaving and are not completely consistent, for example **[Prop Clipping](https://wiki.sourceruns.org/wiki/Prop_Clipping)**. *bind "key" "save hard"* to make a hard save and *bind "key" "load hard"* to load it.

- In certain scenarios, you might find yourself needing to load an autosave or a penultimate quicksave. You can bind keys for these actions, avoiding having to navigate through menus. Type *bind  "key" "load autosave"* and *bind "key" "load quick01"* into the console.

- On Windows, *bind "key" "save :; reload"* will allow you to perform the optimal method for **[Save Deletion](https://wiki.sourceruns.org/wiki/Save_Deletion#Post-Steampipe)**. Use *bind "key" "save <; reload"* if you're running Linux.

- *bind "key" "toggleconsole; unpause"* is necessary to perform **[Quantum Pause](https://www.speedrun.com/bms/guide/ub2k7)**.

- If you are having trouble with your binds not getting saved, type *host_writeconfig* into the console after binding desired keys.

## Setting autoexec.cfg

Some settings reset upon restarting the game. To avoid having to manually type the commands into the developer console each time the game is restarted, we use an  autoexec config.
You should find the config file under *Program Files (x86) → Steam → steamapps → common → Black Mesa → bms → cfg → autoexec.cfg*. If the file is not present, create a new text document and name it **autoexec.cfg**. Open the file and type *cl_showpos 1* and *cl_showfps 1*. Then click *File → Save As... → autoexec.cfg* and save under *All Files*.  These commands will let you see your position in the current level as well as camera angles and most importantly a units per second counter, which shows your current velocity. It also shows an fps counter and current map name, which can be beneficial when managing splits.

https://i.imgur.com/hh94Azh.png
*cl_showfps and cl_showpos*

# Choosing the category

There are three main categories to choose from:

- **No Void** - The preferred category. It's the fastest category in real time, allowing skips (sometimes full chapter/level skips) that are not Voidclips. Having the player character and/or their hitboxes fully surrounded by the void at any moment is forbidden. Void is defined as any space in the map that is not fully enclosed by solids.

- **No Clipping** - Recommended category for starters. No clipping through solid props, brushes, displacements and other level geometry is allowed. This category is all about taking shortcuts and mastering movement through the levels. No significant skips are involved.

- **Any%** - Complete the game from start to finish utilizing Propclips, Voidclips and any other means that are not considered cheating. All glitches are allowed. Due to low demand, this category is currently hidden.

You can also choose to only run Earth levels. Runs in the **Earthbound** category end as soon as you jump into the portal at the end of Lambda Complex. The opposite of this, **Xen levels** category, starts in the first map of Xen and ends with Nihilanth's death.

# See also

- Other guides in the **[Guides](https://www.speedrun.com/bms/guides)** tab for in-depth explanation of some of the tricks.
- Our **[Discord server](https://discord.gg/7XaMbSM)**! It's the place to ask for help. We will be happy to help you.
- the_kovic's Black Mesa speedrun tutorial (2021)
https://www.youtube.com/watch?v=prIanpNfwRE&list=PL0WAeJTbS25k_h_sMUHchf9kfuT82oqQn

Glitch - [1.0] [0.91] [xengine] - Quantum Pause

https://www.youtube.com/watch?v=Vvz0KaYCu3g
[small]This is the video showing the discovery of this glitch.[/small]

**Quantum Pause** is a glitch that makes the player stuck in place while their speed and position can still be affected. It is mostly used to jump to later sections of the game.

It was found by 2838 on November 24th, 2018.

[section=How-to]
- Pause the game (preferably with the *Open developer console* button)
- Enter *unpause* into the console.
The player can simplify this process with a button bound to the command *toggleconsole;unpause*
To end the glitch, simply exit out of the menu screen.

[section=Effects]
## Position
During the glitch, the player's position is almost fixed but it can be affected by many elements.

**Props**
Props pushed towards or falling onto the player will only push them by a small amount, usually a few units.

**NPCs**
Friendly NPCs will phase through the player when attempting to block their path.
Hostile NPCs, however, can push you with their attacks; although like props, they can only push you by a bit. An exception to this is the Barnacle as it forcefully pulls the player upwards towards them using its tongue.

**Doors, elevators, trains, ... **
Scripted props such as doors, elevators and trains will push you similar to how they push away normal props.
If you do the glitch while standing on a moving elevator or train, however, you will ride it like normal.

**Miscellaneous**
Entities or operations that forcefully change your position such as a level change or teleport will still work like normal.

## Speed
Like with position, the player's speed is almost fixed but it can be affected by knockback from:
- Explosive damage or enemies' attacks,
- Props pushed towards or falling onto the player.

**Speed limit**
If the player is on the ground when they do the glitch, their speed will not go over 320 units per second. However, in the air, the player can receive speeds up to 19166.96 units per second.

**Push**
When the player ends the glitch, they will be pushed in the direction and at the speed from knockback they had taken during the glitch. The player can use this force to jump to higher or later parts of the map.

[section=Utilization]
## Position
Because your position is almost fixed during the glitch, you can stay put in the air if you were to activate the glitch while in the air. This is particularly useful when you need to stay inside a trigger normally out of reach from the player. A good example of this is the second half of the Questionable Ethics skip.

https://www.youtube.com/watch?v=emt9TZJMOfk

## Speed
The glitch is a good way to maximize the amount of speed taken from a damage boost (normally from a grenade or two). A good example of this in action is the Advanced Freezer skip utilizing 2 grenades, one on the ground and one held at a steep angle pushing the player towards a higher point of the map, which in this case, is the balcony after the Freezer.

https://www.youtube.com/watch?v=XI7Bi8fj-DY

You can also gain lots of speed from enemies' attacks such as the Human Grunts' punch; however it is harder to execute because of the random nature of NPCs and your vertical speed being dependent on your height relative to the Grunt's. This is best shown in the Canyon skip.

https://www.youtube.com/watch?v=buctod-M3Kw


[section=Notable uses]
**bm_c1a2c - [Advanced Freezer skip](https://www.youtube.com/watch?v=XI7Bi8fj-DY)** - skips the Freezer in the map *bm_c1a2c* of Office Complex.
**bm_c2a4f - [Questionable Ethics skip](https://www.speedrun.com/bms/guide/t4sjg)** - skips the majority of the chapter Questionable Ethics.
**bm_c2a5c - [Canyon skip](https://www.youtube.com/watch?v=buctod-M3Kw)** - skips the entirety of the map *bm_c2a5c* of Surface Tension.

Glitch - [1.0] [0.91] [xengine] [MOD] - Floor Warp

**Floor Warp** is a glitch that causes the player to be clipped down into the floor after entering a map transition.

[section=How-to]
The glitch depends on how maps are made so for every instance of Floor Warp, there is a different way of triggering it. Although all involves touching a wall when entering a map transition trigger. 

[section=Explanation]
Floor Warp happens when the player is stuck at any point during the map transition. Exactly how the game handles this is still unknown due to being obscured by tons of code.

This can be the case if the transition area between 2 maps is badly made with walls or props not aligning to each other correctly. This can be seen in the Ninja Clip

https://i.imgur.com/PnzFA3u.png
[small]Base of the metal beam in both maps, if the player presses themselves against the beam on the previous map, they'll be stuck on the current one.[/small]

Sometimes when the player is between 2 sloped surfaces which are not world brushes (i.e. func_brush, func_detail, ...), they can get stuck due to the weird collision caused by them running into the surfaces. This can be seen in the first half of the Questionable Ethics skip

https://i.imgur.com/5L2cKMb.png
[small]The 2 sloped surfaces the player walk between and touch while entering the map transition.[/small]

Once the game notices you're stuck while transitioning maps, you will be instantly pulled down into the floor similar to Save/Load Buffering while in stuck in a brush.


[section=Notable uses]
**bm_c2a4f - [Questionable Ethics skip](https://www.speedrun.com/bms/guide/t4sjg)** - skips the majority of the chapter Questionable Ethics.
**bm_c3a1b - [Ninja clip](https://www.youtube.com/watch?v=9cVcinMgxq4)** - skips the entirety of the map *bm_c3a1b* of Lambda Core.

Glitch - [1.0] [0.91] [xengine] [MOD] - Save/Load buffering, Voidclipping

[section=Save/Load buffering]
Save/Load buffering is the act of saving and then loading back to that save. 
Save/Load buffering is most commonly used while being stuck inside a displacement or prop to clip downward through brushes and into parts below, skipping sections of the game.
Save/Load buffering is also used to open some closing doors in Surface Tension and Forget About Freeman.  

## How-to
To do Save/Load buffers, simply press your quicksave key, then follow it up by your quickload key. You can simplify this process by binding a key to the command *save quick;load quick*

## Movement while inside brushes
The inner-workings of movement while having speed inside brushes is obscured and fragmented under tons of code; therefore, it hasn't yet been fully discovered. The content below will only show what usually happens when doing specific things with clipping.

Before clipping entirely into the brush, the player can damage themselves using explosives or take damage from enemies, receiving knockback and in turn, giving them speed. This speed can be preserved and used between every Save/Load to make the player move inside brushes in different directions at different speeds. While inside a brush, the speed collected before will not change unless they get knockback from something else.
When the player is entirely inside brushes they can change their speed by doing a Gaussboost, although it can only give you horizontal speed and almost no vertical speed.
Although there is a limitation to this, as you can only move inside the brush you initially clipped into and any brush immediately below you. Trying to boost yourself into a different brush you're currently in and then buffer will result in you either bouncing away or stopping right in front of the brush. 

## Explanations for downward movement
There are 2 functions CBasePlayer::Restore and FixPlayerCrouchStuck that the game calls when loading a save. CBasePlayer::Restore calls for various other functions when you load save and one of those is FixPlayerCrouchStuck but only if the player is crouched.

https://i.imgur.com/uuUjwgb.png
[small]Part of code showing this[/small]

Most methods of getting inside brushes involves crouching and you can't uncrouch while in brushes; so this is always called when you're stuck in a brush.

FixPlayerCrouchStuck is a hack by Valve to find free space when you're stuck in a brush and you're crouched.

https://i.imgur.com/oXWdh35.png
[small]Part of code showing this.[/small]

What it was supposed to do was to pull the player up by 1 units sequentially until the player has moved up by 18 units, check at what point the player is no longer stuck then put the player at that point. If the player does not get unstuck, it will instead do the same operation but now pull the player 18 units down.

But the code was extremely poorly written and what ends up happening is that after the game pulls them 18 units up, it then resets their position and pulls the player 18 units down then does nothing if the player is still stuck, leaving the player 18 units below the ground.

https://i.imgur.com/mIuE358.png
[small]Flaw shown. Note how after *return*, nothing follows.[/small]


[section=Voidclipping]
Save/Load Buffering in the Void incorrectly will discard all speed received before entering the Void; as in the Void, your speed and it's direction can only be preserved between Save/Load's while the game is still loading a save. In essence, you can only move through the void using the speed you've gained by Save/Load buffering once, and then doing another one while the game is still "frozen" and showing the **LOADING** textbox on the screen.

This kind of Save/Load Buffering is commonly known as Voidclipping, and to consistently do Voidclips, you will need to time your Save/Load buffers.

## How-to
**Timing Save/Load buffers**
The time you'll need to wait between Save/Load buffers depends on your PC and the area of the game you're in, although it is usually around 0.5 to 2.5 seconds. 
You can see how much time you'll need to wait by:
- Starting the in-game time timer in Livesplit,
- Going on any map
- Doing a single Save/Load buffer anywhere on that map (particularly in the spot where you begin your Voidclipping). 
- While the game is still loading the save, take a look at the timer. Do another Save/Load while the timer is paused, a little after you did your first Save/Load and right before the timer resumes.
- Do this again and again, making sure the timer **stays** paused and the game is frozen, showing the **LOADING** textbox. After you've chained a few Save/Load buffers, you should get the rhythm down for Voidclipping.

**Seeing where you're going**
Because you need to keep the timer paused while the game is loading a save, in turn the game will not give you any visual indication of where you are in the Void. This is crucial as you can overshoot your desired destination.
To see where you are in the void, simply stop Voidclipping. The game will finish loading back from the save, showing where you are. To start Voidclipping again, 
- Press your quickload key
- While the game is still loading up again, initiate another session of Voidclipping.

**Gaining speed**
--*While about to enter the Void*
When you are half-in, half-out of a brush and about to enter the Void, apart from the weapons you can always get speed with while inside brushes like the Gauss, damage boosting or getting knockback while in this state will still give you speed without being reverted immediately back to 4.69 UPS. 
Although all explosives (except the Tripmine as it cannot be placed OOB) will give your speed, it is recommended that you stick to the SMG Nade because of it's relatively high accuracy when fired. Other methods of knockback like the Hivehand is also recommended as it has unlimited ammo and is also relatively accurate and quick to gain speed with. This is best shown in  [The bm_c3a2h skip](https://www.speedrun.com/bms/guide/kwv7k)

--*While inside the Void*
Similar to boosting inside brushes, you can use the Tau gun to gain speed in the middle of the Void. However this is very difficult and relies on your PC hardware and peripherals. Only do this when your clip goes wrong!
- Charge up the Gauss while aiming at the appropriate direction. 
- At the same time you release your right mouse button to stop charging and execute a Gaussboost, press your Save/Load key. You will know that you've succeeded if your Velocity has changed and you've moved.
The speed given by the boost will only appear for a single frame, so you will need to minimize the latency of your mice, keyboard and monitor to time it correctly. 
Along with minimal latency requirements, at framerates lower than 60 FPS, you will never gain the speed given by the boost, so you will need to ensure the best game performance while doing this trick.

**Caveats**
--*Overshooting and Undershooting your destination*
If you have overshot your destination, you can load back to your 2nd quicksave by loading the second quicksave in the "Load Game" menu or you can put in *load quick01* into the console. Usually when you do this, you will be right above your destination.
Normally, if you've undershot your destination by not having enough momentum, you'll have to redo your clip entirely. 

If you are instead, stuck in the void clipping down onto a section not of your destination's; if that section and your destination are under the same ceiling (or have ceilings that are touching and are ≤18 units above or below each other), you can:
- Continue clipping downwards until you are near the roof of that section
- When near, release Control and slowly Save/Load down until your velocity drops to 0.
- When your speed is at 0, stop Save/Loading and walk around until you are right above your destination
- When you are above your destination, Save/Load to go down into you destination.
This method is very risky and can fail easily if you don't stop buffering at the correct point; only use this if you are sure of the position of the ceiling you're lowering into.
Movement while on these ceilings are described in the **Movement** section down below.

--*Doing buffers too quickly*
Doing Save/Load buffers too quickly will result in the game not showing the **LOADING** textbox while loading saves and instead showing the load screen you see when you start up a map or a save right after launching the game. If this happens, you will **not** be able to properly chain your Save/Load buffer again, but you can do the following instead:
- After going through the load screen, press your quickload key
- While the game is still loading up again, initiate another session of Voidclipping.

--*Doing buffers too slowly*
Doing Save/Load buffers too slowly will result in failing the Voidclip completely. If your very last save was done too slowly, you can:
- Open the menu and load your second-to-last quicksave (or put *load quick01* into the console)
- After the game had loaded back up, press your quickload key and initiate another session of Voidclipping.
However, if all 2 of your available quick saves are done too slow, you will need to redo the Voidclip again.

## Movement while Voidclipping
The inner-workings of movement while being inside the Void is obscured and fragmented under tons of code; therefore, it hasn't yet been fully discovered. The content below will only show what usually happens when doing specific things with clipping.

**General movement inside the Void**
Movement while Voidclipping is similar to Save/Load buffering in brushes. However unlike Save/Load buffering, you can break the Voidclip by waiting for the game to finish loading and begin buffering to clip directly down, through all brushes and props. To clip down faster, hold crouch while buffering.

**Movement while on a surface**
While voidclipping, if you are ≤18 units above any surface, you will immediately be put on them. 
On these surfaces, you can walk around freely; however walking off these surfaces will put you back stuck in the void with no speed. If another surface is ≤18 units above the surface you are currently standing on, you can walk directly onto that surface and vice versa.
If you are crouched while on these surfaces, you can not uncrouch.
If you jump, you will go up for a few units and then get stuck in the void. You can drop back down again by Save/Loading. However, if you Save/Load at the correct time a little bit after jumping, you can begin Voidclipping at the speed and in the direction of your jump before.
This kind of movement is best shown in the **bm_c1a1c skip**:

https://www.youtube.com/watch?v=GFztfHyj_aY
 
 

[section=Notable uses]
[big]**Save/Load buffering (boosted, clipping in and out of same brush)**[/big]
**bm_c1a4e - Blast Pit skip/Tentacle skip** - skips the majority of Blast Pit.
**bm_c2a1a - [Power Up skip](https://www.youtube.com/watch?v=ERlIPWm6DA0)** - skips the entirety of Power Up.
**bm_c2a5h - [Barney skip](https://www.youtube.com/watch?v=rjQ4yu48Jmw)** - skips the majority of the map *bm_c2a5h* of Surface Tension.

[big]**Voidclipping (retaining speed)**[/big]
**bm_c1a1c - [bm_c1a1c skip](https://www.youtube.com/watch?v=GFztfHyj_aY)** - skips the entirety of the map *bm_c1a1c* of Unforeseen Consequences. 
**bm_c1a3a - [Weve Got Hostiles skip](https://www.youtube.com/watch?v=T7GIQfrMXsw)** - skips the entirety of We've Got Hostiles.
**bm_c3a1b - [Ninja clip](https://www.youtube.com/watch?v=9cVcinMgxq4)** - skips the entirety of the map *bm_c3a1b* of Lambda Core.
**bm_c3a2b - [c3a2b Fight skip](https://www.youtube.com/watch?v=sS7URQJ1JcM)** - skips the entirety of the map *bm_c3a2b* of Lambda Core.

Skip - [1.0] [0.91] [xengine] [MOD] - Apprehension Cutscene skip

https://www.youtube.com/watch?v=Dx9VMeGWJgo

**Apprehension Cutscene skip** skips the entirety of the second map of the Apprehension chapter. It saves around 50 seconds to 1 minute if done well.

It was first conceived on December 31st, 2018 and first done on June 7th, 2019 by 2838.

[section=How-to]
##Preparing for the clip
- Do a chapter select when you enter Apprehension when you first enter the chapter to regain all your ammo and health.
- While swimming through the door you open after first encountering the ichthyosaur, grab a barrel under the water and bring it up out of the water.
- Continue carrying that barrel until you reach this point near the end of the first map and kill the barnacle.

https://i.imgur.com/2okCO7N.jpg

- Stand right in front of the button as close as possible.
- Now start running backwards and after you step over the shadow of the catwalk above, press the button and jump.
- You should end up down at the middle of the flight of stairs with the barrel you've place beforehand with the walls being all weird and LSD-like.

##Clipping
- Now take the barrel and head down to the end of the stairs.
- Place yourself like this and then do a propclip.

https://i.imgur.com/kal0J13.png

- Once in the ground, put down a tripmine at angles 50 x and -176 y. Once it explodes, put down a satchel, hold it and look directly down to the ground and aim at -176 y then detonate it.
- After boosting, initiate a Voidclip until you get to this hallway.

https://i.imgur.com/lvtdOfj.png

- Now clip directly down and then go down the hallway to the big room.
- Put down your last trip mine like this directly below the left vent. 

https://i.imgur.com/2j40Mzf.png

- Run and do a SMG nade boost directly above the trip mine to reach that vent.
- Once in that vent, you can now go through it, triggering the map change.

[section=Explanation]
##Why do we need to put the barrel there?
We need to put it there to make sure it's properly carried onto the next map. If it is anywhere not near the flight of stairs, in the next map it would not be there.

##Why do you end up behind there?
This is a flaw in map design that miraculously hasn't been patched out ever since it's first appearance in the MOD version.

When you press the button to open the door and go to the next map, there is a brief pause for the button to finish it's animation before the map changes. 
To put simply how the game puts you after the map change, if we were in the hallway before the stairs in the last map, then on the next map we will be put in the same spot where the hallway would have been if it had existed.

https://i.imgur.com/Xp91FHM.png

In the second map the trigger responsible for going back to the first map is placed too close to where the button is, so if you jump at just the correct time, you'd end up behind it on the second map.

https://i.imgur.com/IcUhcU8.png

##Why are the walls here so trippy?
The walls which have the trippy visuals have the nodraw textures applied. Normally, when nodraw textures are used on a face of a brush, they should not have anything shown on that face. But combined with cubemaps, all weird things can happen.

https://i.imgur.com/pOEzXtr.png
[small]The space in Hammer Editor[/small]

Skip - [1.0] [0.91] [xengine] [MOD] - Residue Processing intro skip

https://www.youtube.com/watch?v=0957rf88CS0

**Residue Processing intro skip** skips the long intro sequence with the crusher at the beginning of the Residue Processing chapter. It saves around 40 to 45 seconds if done well.

It was found by Varial on December 7th, 2018.

[section=How-to]
- After gaining back control, go up to the control room as fast as possible.
- Grab the bucket on the shelf and then head down back to the crusher.
- Jump on the box and hold the bucket like this.

https://i.imgur.com/BNVADEc.jpg

- Now crouch ram the bucket into the crusher while still standing on the pile of crates.
- If done correctly, the bucket should go right through the crusher.

https://i.imgur.com/WUjurIo.png


- Now stand and run and jump down onto the space behind the crusher wall behind you.
- Ram the bucket into the crusher wall like so.

https://i.imgur.com/oYZ6Eas.png

- Keep ramming it into the wall, making sure that you're inside the bucket. Once you stop moving, save/load. You should now start clipping into the floor.

[section=Explanation]
##Why does the bucket lose collision and go through the crusher?
The crusher wall is actually a *func_door* but moving sideways. It's *Blocking damage* property is set to 1000 and *Force Closed* set to True, meaning for every frame, the game will damage any prop or object blocking the door by 1000 HP. So if you use any breakable prop (such as wooden crates) to block the door, it will break as normal. However, if you use an unbreakable prop like the cone, what the game will do is to temporarily disable collision for the prop, allowing us to get stuck in it and clip with it.
In this case, as we push the prop against the crusher wall, the game will think that the bucket is blocking the crusher wall, thus temporarily disabling its collision.

https://i.imgur.com/aKp9azV.png
[small]Part of code executing this.[/small]

Skip - [1.0] [0.91] [xengine] [MOD] - The bm_c3a2h skip

https://www.youtube.com/watch?v=zH7g2mpD8Vw&feature=youtu.be
[small]This video shows the old method for boosting for the Voidclip which is much more random and prone to failure. Please refer to the How-to section below for instructions[/small]

**The bm_c3a2h skip** skips the majority of the bm_c2a3h map of Lambda Core. It saves about from 1 to 1 and a half minutes if done right.
It was found by 2838 on April 22nd 2019.

[section=How-to]
## Getting into position
- When you enter the map, Save Delete. You need to do this to get sufficient ammo and health.
- Continue through the map as normal until you get to the big glass door with the broken turrets where the cutscene starts. Turn around and grab the while **COOLANT** barrel.
- Go back to the ladder and line yourself up with this line on the floor

https://i.imgur.com/lefyumg.jpg

- Now take the barrel and look at about -179 yaw and do a propclip with the barrel. Remember to keep yourself aligned on that line when you clip.
- After clipping, keep Save/Load buffering until your z coordinate is from -145 to -155.
- Make sure that you are still clipped inside the wall of the elevator shaft by checking if your velocity is anything but 4.69 UPS. If it is 4.69 UPS, that means you are no longer clipped inside the wall and you are in the Void. If this happens, redo the clip and correct your position.

## Voidclipping to the end
- When in position, aim at 70 pitch and put your crosshair on this line here 

https://i.imgur.com/cIMwcoV.jpg

- Switch to your SMG and fire all 3 SMG Grenades; then switch to the Gauss and Gaussboost using all of your ammo.
- Now switch to the Hivehand and aim at 40 pitch while still having the crosshair on that line. Fire a few bolts until your speed reaches 2000UPS.
- Save/Load once, then turn your FPS down to 30.
- Continue Save/Load buffering and turn your FPS back to normal when you're over the ceiling of the supply depot, which is where the cutscene'd take place. 
- Continue Save/Load buffering until you're right above the airlock at the end.

https://i.imgur.com/fkUzqUQ.png

- Now simply Save/Load buffer until you fall on top of the fan 

https://i.imgur.com/nr1MwsV.jpg

- Walk off the gap around the fan to drop down and finish the skip.

[section=Explanations]
## Why clip down through the shaft?
As mentioned in the Voidclipping [guide](https://www.speedrun.com/bms/guide/qjt0l), you *cannot* clip through a brush from the side or from below, you have to go above a brush to be able to clip into it from the Void. In this case the airlock has an unusually tall ceiling.

https://i.imgur.com/kJda3P6.png
[small]The airlock viewed in Hammer Editor[/small]

The community has tried many ways to start the clip along the main hallway, but to no avail as the map geometry didn't allow that to work as wanted. Another problem is that you would need a lot of vertical speed in order to get over the big blue-ish turbine room. If you were to try to get a lot of vertical speed to get over it clipping from the hallway then you'd rise back up from the ground, ending the clip prematurely every time; the same is true with horizontal speed.

The path from the shaft has the least amount of things that we could collide during the clip. We need to minimize the things we bump into as they could affect our path toward the airlock at the end, especially when its' ceiling is so small.

## Why 30FPS?
Because we have to go so far upward in such a relatively small space, we will need to do everything possible to maximize the amount of height gained from the boost. For unknown reasons, switching to 30FPS while doing Voidclips will help lots in gaining height. And we turn back to our normal FPS after we've gotten over the supply depot to minimize the height we get there; as we'd want to be as close as possible above the airlock's ceiling to minimize the amounts of Save/Loads needed, thus saving some little time.

## Why can't we clip from the supply depot?
The airlock's walls and floors are entirely separate from those in the supply depot. Similar to Voidclipping, you *cannot* clip into another brush different from the one you're already in if we approach it from the side. So no matter how much speed is gained to clip into the airlock from the supply depot, we will never make it.

Skip - [1.0] [0.91] [xengine] [MOD] - We've Got Hostiles skip

https://www.youtube.com/watch?v=T7GIQfrMXsw

**We've Got Hostiles skip** skips the entirety of the We've Got Hostiles chapter. It saves around 2:30 to 3 minutes depending on how well you do the skip and how well you do the We've Got Hostiles chapter.

It was found by 2838 on June 26, 2018.

[section=How-to]
##Preparing for the clip
- Do a chapter select when entering We've Got Hostiles to regain your health.
- Run and pick up the traffic cone off the ground, then bring and drop it near the gate.
- Keep running through the corridor around the corner and pick up the grenades near the turret ambush.
- Turn back to the suit charger and charge until you have around 40 suit energy.

##Getting into position
- Once done charging your suit, turn back and grab the cone previously placed near the gate.
- Place the cone so that it is right under the closing gate, making sure the gate will crush the cone. At this point you should make a hard save.
- Once the cone has lost it's collision and start going through the gate, immediately get back up and jump on the pile of metal crates near you.
- Jump onto this ledge above the crates and above the singular crate like this.

https://i.imgur.com/SvLKJ7k.jpg
[small]The cone is removed for more clarity[/small]

- Crouch, look and walk into the wall, making sure the cone is inside you like this. Double tap E once the cone touches the wall to ensure that you don't drop the cone.

https://i.imgur.com/joCNBAz.png

- Once the sirens of the door has ended, save/load once. You should now be inside the wall.

##Doing the clip

- Once inside the wall, throw the cone away and throw a grenade anywhere within these tiles. Make sure that the grenade doesn't go too far and end up touching the wall opposite the one you're in.

https://i.imgur.com/yHoceiz.jpg

- When it detonates, make sure that it's explosion increased your velocity. If so, save/load once, you should move down further into the wall. If you pop back out, reload your second-to-last save to retry.
- Now throw 3 grenades sequentially, each one you hold and aim at angles 50 x and 175 y although you can deviate from that by a few degrees. It is recommended that you throw them at this wall to make grabbing easier.

https://i.imgur.com/BD1zrkS.jpg

- Initiate a [Voidclip](https://www.speedrun.com/bms/guide/qjt0l) with the speed you've gained until you're above the area behind the closed gate leading to the Blast Pit chapter like so.

https://i.imgur.com/U2tRCBb.png

- Now clip directly down and you're done!

[section=Explanation]
##Why does the cone lose collision?
The gate closing down on it has its *Blocking damage* property set to 50 and *Force Closed* set to True, meaning for every frame, the game will damage any prop or object blocking the door by 50 HP. So if you use any breakable prop (such as wooden crates) to block the door, it will break as normal. However, if you use an unbreakable prop like the cone, what the game will do is to temporarily disable collision for the prop, allowing us to get stuck in it and clip with it.

https://i.imgur.com/aKp9azV.png
[small]Part of code executing this.[/small]

##Why do I need to throw the first grenade?
When only a small of you is clipped into the wall, the game will automatically push you out the other way to un-stuck you. To counter this, we need to throw a grenade in such a way so that the speed gained from the knockback caused by its explosion will keep us inside the wall but not push us too far into the wall that we are entirely inside it. If that happens then you can't boost yourself to do the voidclip.

This is also why you shouldn't throw the nade too far that it ends up touching the leg of the opposite wall, as it's knockback would be too small to counteract the game's push.

[section=See also]
[Voidclipping](https://www.speedrun.com/bms/guide/qjt0l)

Skip - [xengine] [MOD] - Questionable Ethics skip

https://www.youtube.com/watch?v=DVIZTDRrfc8
[small]This video is the original video first showing the skip, so it uses outdated ways of doing it. Please refer to the How-to section below for instructions.[/small]

**Questionable Ethics skip** skips the majority of the chapter Questionable Ethics. It saves around 3 to 5 minutes depending on how well you do Questionable Ethics

It was found by 2838 on July 31st, 2018 with improvements from Table and the_kovic.

[section=How-to]
## Getting under the floor
- Start by chapter selecting Questionable Ethics when you enter the it's first map.
- Once the map has loaded back up, continue progressing onward through the map until you get to the corridor where you transition to the next level.
- Jump onto this part of the wall where there are a lot of pipes.

https://i.imgur.com/R5cRmCi.jpg

- Begin walking against the wall by turning your mouse slightly to the right to face the wall and walking forwards. If you get stuck, stop, wait a split second and start walking again.
- Continue walking against the wall until you transition to the next level.
- Upon loading the next map, you should be firmly stuck in the wall like this. You'll know that you're stuck in the wall if you can't move and your speed is at 4.69 units per second.


- If you're stuck in the wall, begin [Save/Load buffering](https://www.speedrun.com/bms/guide/qjt0l) until you pop back out under the floor.

## Transitioning maps
- Invisible walls under the door in the level change room form a corner; walk to that corner.

https://i.imgur.com/UWcT9vk.jpg

- Switch to your satchel charge and place a satchel down at the ground. It is recommended that you hold the satchel after throwing it and the place it right behind you so that it pushes you into the corner when it is detonated. The corner of the skybox is a good lineup for where you place the satchel.

https://i.imgur.com/UHPxi7b.png
[small]Skybox satchel lineup[/small]

- After putting down the satchel, do a damage boost using the satchel by jumping and detonating it.
- When your head hits the "ceiling" under the door, do the [Quantum Pause glitch](https://www.speedrun.com/bms/guide/ub2k7).
- Wait 2 seconds and you should transition into the next map.
- Once you're in the next map, you'll be stuck underground. To get back up simply do a [Save Delete](https://wiki.sourceruns.org/wiki/Save_Deletion).

[section=Explanation]
## Why am I in the wall?
This is due to [Floor Warp](https://www.speedrun.com/bms/guide/yg4e8), more specifically due to these 2 sloped surfaces on the wall you stand between and touch causing you to be stuck during the map transition

https://i.imgur.com/5L2cKMb.png



## Why do I damage boost?
There are 2 triggers responsible for transitioning maps: a *trigger_changelevel* that is responsible for the transition itself, and a *trigger_once* that triggers the *trigger_changelevel* as it doesn't trigger from player touch.
When making this map, the developers extended both triggers beyond the room they were supposed to be in, so a bit of them stick out the corner of the room.

https://i.imgur.com/xrp26FD.png
[small]Both triggers sticking out of the room, viewed in Hammer Editor[/small]

Because of this, the player can hit this trigger to change maps from outside the room, however this trigger is out of reach from the player, even when jumping. As a result, you will need to damage boost yourself to hit the trigger.

## Why do I need to do Quantum Pause?
When attempting to do the skip without Quantum Pausing, after you hit the *trigger_once* and falling back down, nothing will happen. This is because trigger work like this:
- The trigger has an I/O connection of this:

https://i.imgur.com/6k3FhES.png

So when the player starts touching the trigger, it will wait for 2 seconds and then fire the output *ChangeLevel* to the *trigger_changelevel* (which in this case is called *bm_c2a4f_bm_c2a4h_t*). This output will tell the *trigger_changelevel* to transition maps.
- However after the delay of 2 seconds, it will check if the player is still making contact with the trigger or not. If the player only attempts to hit the trigger once; the trigger will not fire the *ChangeLevel* output to the *trigger_changelevel*, and in turn, failing the map transition. The console command *developer 2* shows the message that the *trigger_changelevel* sends out when this happens.

https://i.imgur.com/xeXXi0w.png
[small]Message sent out by the *trigger_changelevel*[/small]

Quantum Pausing in midair so that the player is always inside the trigger will pass the checking done by the *trigger_changelevel*, and in turn, transitioning maps.

## Why am I underground after transitioning?
A simplified explanation for this is because you are under the map transition room's floor in the last map, on the next map you will be put under the floor of the same room. And since under that room are brushes and the void, you will be stuck inside them.

https://i.imgur.com/N1mfLTk.jpg
[small]Player stuck underground after transitioning maps[/small]

https://i.imgur.com/gqmCZJr.jpg
[small]The area the player'd be stuck in when transitioning maps, shown in Hammer with all *nodraw* textures hidden[/small]

[section=See also]
[Floor Warp](https://www.speedrun.com/bms/guide/yg4e8)
[Save Deletion on the SourceRuns wiki](https://wiki.sourceruns.org/wiki/Save_Deletion)
[The Quantum Pause glitch](https://www.speedrun.com/bms/guide/ub2k7)

Name	Author
[Video Tutorial] Black Mesa Speedrun Guide (2021)	the_kovic 3 years ago
Getting started	Table 10 months ago
Glitch - [1.0] [0.91] [xengine] - Quantum Pause	2838 5 years ago
Glitch - [1.0] [0.91] [xengine] [MOD] - Floor Warp	2838 5 years ago
Glitch - [1.0] [0.91] [xengine] [MOD] - Save/Load buffering, Voidclipping	2838 5 years ago
Skip - [1.0] [0.91] [xengine] [MOD] - Apprehension Cutscene skip	2838 5 years ago
Skip - [1.0] [0.91] [xengine] [MOD] - Residue Processing intro skip	2838 5 years ago
Skip - [1.0] [0.91] [xengine] [MOD] - The bm_c3a2h skip	2838 5 years ago
Skip - [1.0] [0.91] [xengine] [MOD] - We've Got Hostiles skip	2838 5 years ago
Skip - [xengine] [MOD] - Questionable Ethics skip	2838 5 years ago