https://starmen.net/vote/vote.php?id=23586

(the download link is the green version of the hack's name on the page)

Weird Point sources that are in the speedrun route: (note: finding a key/crest "quickly" means finding it without having looked for it anywhere else since the last key/crest. Kinda like how in BaS/TaT we avoid weird-point-related long dialogues later on by checking the place right next to the 3rd star crest before picking it up. Note that "quickly" is completely separate from "before having seen what it's needed for")

Find first crest before seeing tears cutscene: +1

Stay silent/don't listen in the cutscene before first Sadness fight: +1

Find key in library without having interacted with the door, but without having found ALL of crests 1, 3, and that key itself, quickly: +1 (happens in BaS/TaT route)

Find key in library quickly (regardless of if you've checked the door) after finding crests 1 and 3 quickly: +5 (happens in True Ending route)

Find final star crest quickly after finding all other crests and keys quickly: +5 (happens in True Ending route, pretty long dialogue which is why we avoid this in BaS/TaT)

Find torch without having interacted with the hair: +2 (+1 at torch and +1 after burning the hair. The latter gives longer dialogue if you already had 10 Weird Points before it)

There are many other sources, some of which could potentially be used to make True and Perfect branch out later than Library in AME

Weird Points are in fact the only condition - True Ending is possible when you have at least 10 Weird Points by the time you reach the Last Hallway (the room where the Candy Scene happens in that ending), while Perfect Ending happens when you have less than 5 when you reach the Last Hallway. Both can only happen after having gotten In Blood and Stars and/or In Tears and Time at least once (repeating In Blood and Stars/In Tears and Time can be done by either having 5-9 Weird Points, or losing the King fight on the True Ending path. In the latter case, In Tears and Time will be guaranteed if Siffrin has TimeFreeze state at the end of the battle [that can technically also happen on the "normal" path, but only if you force the OHKO cutscene move - which has a chance of applying TimeFreeze - by doing 12000 damage to the King])

As for the sources of Weird Points, I haven't yet looked into all of them, but I think the biggest source we get in the normal True Ending speedrun is a +5 from always picking up keys and crests without checking anywhere else in the room (it's the extra reaction and choicer that the TE part of the run gets on picking up the final crest during hair puzzle)

If I understand these current rules correctly, they would allow making a save some time after BaS/TaT but before locking in to either route (i.e. less than 5 weird points, and still with potential to reach 10 weird points), and then making the Perfect End and True End branch out of that save (as opposed to doing Bas/TaT->Perfect->True with each one taking a full loop, and as a result having Memory of Perfection in your inventory when you do True End)

IDK if this is good or bad though.

I think it'd be a better idea to do All Major Endings (IBAS/ITAT+Perfect+True, instead of requiring both IBAS and ITAT) rather than a full All Endings, because IBAS and ITAT are a coinflip (at least when going for IBAS. With ITAT, having Siffrin be frozen at the end of the battle does apparently force it?) and there's a 50% chance that you just get the same one twice, which would automatically kill the run (or lose several minutes if you're doing a no reset) in an All Endings/All Memories/All Items category. Which just... seems VERY unfun to put the whole run at the mercy of literal 50-50 RNG, especially over 10 minutes in.

(technically this could be solved by allowing a mod that ensures the 2nd IBAS/ITAT ending will be different from the 1st, but still, it's probably better to address such an issue with the category definition itself rather than a mod)

Download UTMT (UndertaleModTool)

Open the data.win in UTMT

Go to the "Scripts" dropdown from the top context menu, then "Builtin Scripts", then select either "EnableDebug" (debug always on), or "DebugToggler" (can toggle debug with F1, have to manually enable it with that key every time you launch the game or reload your save)

You can also run both of those scripts to make it so that the game loads with debug but also lets you toggle it off when you want to.

This method works for all Undertale versions, most Undertale mods, and the original 2018 release of Deltarune Chapter 1. For the more recent Deltarune Chapter 1&2 demo (including all updates to it so far) you simply need to use a different script, which is called "Ch2 Debug" and found under "Community Scripts".

Step 1: go into the game's properties on Steam. First, go to "Compatibility", and force the "Steam Linux Runtime" compatibility option (by default, it uses Proton which prevents you from getting the Linux version). After that, go to "Betas" and choose "old_version_101", then update the game.

Step 2: if you were previously in GameScope, switch to Desktop Mode. Open the game's properties again through the Steam desktop client, go to "Installed files" then press the "Browse" button. This will open the game's folder. Open whichever place you want to copy the game to in a separate Dolphin window, create a folder for it there, then drag-and-drop the "runner" file and "assets" folder into it and choose "copy".

Step 3: go back to the Steam desktop client. Press "Games" at the top of the window, then select "Add a non-Steam game". Press the "Browse" button, change the Filter from "Applications" to "All Files", and select the "runner" file from the newly copied version of the game.

Step 4: go the properties of the newly added "runner" on Steam, and once again force the compatibility option to "Steam Linux Runtime". You can also change its name in Steam from "runner" to something more descriptive, such as "Undertale fast launch" or "Undertale no Steamworks"

Step 5 (you can skip this if you intend to play on keyboard): set up the game's controls through Steam Input (make sure you do this for the version you manually added, and not the original installation from Steam)

Continuing after a crash is allowed as long as you use a save from the same run, it has been done before in top players' PBs (e.g. 59:52 NoSLA WR by Can't Even [crashed during moonshot attempts] and 28:25 Mel Inbounds by Burger40 [crashed in Transition])