Many speedruns of Hollow Knight are done on previous patches of the game because important skips and glitches have been added and removed over time. That being said, you are never required to run on the most optimal patch, and many runs can be done on current patch if that's what you want to use.
Most speedruns are done on 220.127.116.11 for No Major Glitches or 18.104.22.168 for All Glitches and No Main Menu Storage, but it can vary. If you're unsure, check what patch the run you're following uses or ask in the Hollow Knight Speedrunning Community discord.
Downpatching for Steam
There are two patches that can be accessed very easily through the Beta branches on Steam:
22.214.171.124 - Godmaster final patch, can be used for Current Patch runs
126.96.36.199 - Grimm Troupe final patch, optimal for most other No Major Glitches runs
1) Right-click Hollow Knight in Steam and select Properties.
2) Select the patch you want to use under the Betas tab.
3) Hollow Knight will now automatically update to your chosen patch.
If you want to access a different patch, there are two other options for downpatching through Steam. The first option is to patch Steam to re-enable the old method of downpatching through Steam's console. The second option is to download a separate tool called DepotDownloader, but this tool is awkward to use and has some dependencies. This is why patching Steam should be the first method you try and the details will be listed in the section below.
Downpatching for GoG
This method will only work if you own the game on GoG. If you own the game on Steam you will need to use the Steam method.
Downpatching for GoG is very simple, however currently most useful patches are unavailable through GoG.
1) In GoG Galaxy, under Hollow Knight, select Manage Installation->Configure...
2) Make sure that Auto-updates is turned off.
3) Select whichever Hollow Knight version you need:
188.8.131.52 - Godmaster final patch
184.108.40.206 - Godmaster release patch, used for Pantheon All Bindings ILs
4) Your game will be automatically updated to the chosen patch.
1) Navigate to the Steam console by pressing Win+R and typing "steam://nav/console".
2) Enter the following command depending on the patch you want to download:
220.127.116.11 - Godmaster release patch, used for Pantheon All Bindings ILs Command: "download_depot 367520 367521 7281172781181458959"
18.104.22.168 - Grimm Troupe final patch, used for most No Major Glitches categories Command: "download_depot 367520 367521 648876203478229944"
22.214.171.124 - Hidden Dreams final patch Command: "download_depot 367520 367521 3452389063277773009"
126.96.36.199 - Hidden Dreams release patch, used for 100% All Glitches Command: "download_depot 367520 367521 4098313936262429664"
188.8.131.52 - Used for most All Glitches Categories Command: "download_depot 367520 367521 6521580788679328160"
These are the commands for the most useful patches, on Windows only. A full list for every patch including IDs for Mac and Linux can be found here.
3) Be patient on the download. When it's finished a "Depot download complete" message will appear in the console and you can move onto the Installation section.
If you used the patching Steam method, the old patch files will be in your Steam install folder under "Steam\SteamApps\content\app_367520" and inside another folder.
If you used the alternate DepotDownloader method outlined later, the old patch files you downloaded can be found in the "depots" folder inside a few other folders.
The important files here are "hollow_knight.exe" and the entire "hollow_knight_Data" folder.
If you only want a downpatched version of Hollow Knight installed, you can delete the files in your current Steam install and copy these files there instead. However, there is an easy way to have multiple versions of Hollow Knight installed that I'll outline below.
Multiple Installed Patches
1) Create a folder anywhere you like and name it something that'll remind you it contains your downpatched Hollow Knight version. I created a folder named 1221 in the same location that I downloaded DepotDownloader to. Copy the old patch files here.
2) Create a new text document in this folder titled "steam_appid" and in that document copy only the number "367520". If you have file name extensions showing, the name of document will be "steam_appid.txt", if you don't you'll only see "steam_appid".
3) Optional: Add this install to Steam as a Non-Steam Game so that you can launch it directly through Steam whenever you want.
Saves files are shared across every Hollow Knight installation, regardless of the patch. These files are located at "C:\Users\yourname\AppData\LocalLow\Team Cherry\Hollow Knight".
Launching a current patch save with an older patch version of Hollow Knight can corrupt that save file. If you want to protect your casual save file, you can make a backup of the files in the location specified above.
Deleting Windows Registry
Some people have issues with their game after downpatching from current patch to an older patch. These might include the game crashing or not accepting inputs when sitting at benches, quitting out or some other interactions. If you have weird issues like this, deleting Team Cherry's folder in your Registry might help.
1) Press the Windows button and R at the same to time to bring up the Run command line, enter "regedit" and press enter.
2) Navigate to "Computer\HKEY_CURRENT_USER\Software\Team Cherry" and delete that folder.
The next method outlined below also has a video guide made by Verulean. I'd recommend watching that guide alongside reading this one:
1) You need to acquire .NET Core from Microsoft's website here, make sure to download the current recommended build for your operating system (Windows x64 for most users, but please check this).
2) Launch the downloaded executable and follow the instructions to install .NET
If you're still running Windows 7 you'll need an additional update from Microsoft's website here.
3) Download the DepotDownloader tool from GitHub here. Find whatever the latest release is and make sure to use the first download link, not the source code.
4) Move the .zip to somewhere you'll remember and extract it (WinRAR and 7-Zip are free tools that can extract .zip files)
1) In the extracted DepotDownloader folder bring up the command line at that location by typing "cmd.exe" into the address bar or by Shift + Right-clicking and selecting "Open PowerShell window here".
2) Now you can enter the commands to download the downpatched files for whichever Hollow Knight version you need. The first thing we need is the manifest ID for the patch you want to download.
Listed below are the manifest IDs for the most useful patches, on Windows only. A full list for every patch including IDs for Mac and Linux can be found here.
184.108.40.206 - Godmaster release patch, used for Pantheon All Bindings ILs Manifest ID: 7281172781181458959
220.127.116.11 - Grimm Troupe final patch, used for most No Major Glitches categories Manifest ID: 648876203478229944
18.104.22.168 - Hidden Dreams final patch, used for most No Load Dependent Glitches categories Manifest ID: 3452389063277773009
22.214.171.124 - Hidden Dreams release patch, used for 100% All Glitches Manifest ID: 4098313936262429664
126.96.36.199 - Used for most All Glitches Categories Manifest ID: 6521580788679328160
3) Take this number and replace <manifest> in the following command as well as replacing <username> and <password> with your steam account's details.
dotnet DepotDownloader.dll -app 367520 -depot 367521 -manifest <manifest> -username <username> -password <password>
Pasting your complete command in command line and hitting enter should begin the download. If you have Steam Guard active you will be prompted for your code. The command may not work if your password contains a special character. In this case don't include the "-password" part of the command and you will be prompted for your password instead. Here's an example of me using the code to download patch 188.8.131.52 (manifest ID 648876203478229944).
You will be able to check progress as the patch downloads. Be patient as it will take longer than a normal Steam download.
@Serena and @dewin for the depot and manifest IDs. @Mickely for installing multiple patches and clearing registry. @56 for the Steam patcher tool @Verulean and @56 for using DepotDownloader. @acridstingray3 for GoG downpatching.
Title screen may now be shown at any point during a run, so long as you add a timestamp with your submission. IL runs are unaffected.
You may resubmit runs rejected under the old ruling if you wish for them to be verified.
Video evidence must show the Title Scre