Comment by mimikyu on Exercise: Planmaking, Surprise Anticipation, and "Baba is You" · 2025-01-11T21:13:13.110Z · LW · GW

Ultimate Baba Challenge

Here is a very difficult Baba is You challenge. It's not a level or a levelpack, but the puzzle of creating a level which meets a specific criterion. It took me four days (a few hours per day) to find a solution. It felt analogous to pre-paradigmatic research, gradually building understanding of a thing and encountering apparent paradoxes that seemed to make it impossible.

The criterion is: The level must require the player to undo at least 2 moves while holding a delayed infinite loop trigger in order to WIN.

What does that mean?

I'll try to only spoil the basic requirements.

There is a bug in the game where:

• Toggling "Force high-contrast colors" on or off causes the game to reprocess text on the level.
  • Moving any piece of text also causes the game to reprocess text. Undoing a move of any piece of text does as well. This is relevant to the section on word loops.
• The game reprocessing text 200 times in one turn causes the game to think there's an infinite loop, leading to the infinite loop screen, which destroys the level but can be undone with Z.
• Because this method happens between turns, you can undo any number of moves first, and the level will only be destroyed upon your next non-undo move.

(In other words, the player must at some point be forced to toggle that 200 times, then press Z to undo at least 2 moves, and only then make a non-undo move)

Destroying the level has two effects:

• It reverse the Object Priority of the objects when they are un-destroyed (by undoing the destruction event).
• It breaks any active WORD loops.

What is a WORD loop?

• There is a text object in the game called WORD. FIRE IS WORD makes the fire-object also count as a word. For example, FIRE IS WORD at the same time as [fire-object] IS YOU AND WIN results in winning.

• Given some series of texts like...

  • STICK IS WORD
  • ROCK AND [stick-object] IS WORD
  • FIRE AND [rock-object] IS WORD
  • LAMP AND [fire-object] IS WORD

  After STICK IS WORD is no longer formed: Every time the game reprocesses text, one line of text down will also become inactive; or active, if it was previously inactive but the one above it is active (e.g. if STICK IS WORD was only formed for one turn).

  If it instead ended with FIRE AND [fire-object] IS WORD, that final line would be self-sustaining once activated.

• Notably, undoing text movement does not undo the reprocessing; in fact, it just reprocesses again because undoing moves the text, enabling a form of time travel.

Can I have hints?

You can ask me for hints by replying to this comment.

Are there easier challenges that I could start with instead?

Yes. Here are some:

• Make a level that requires an infinite loop activation at all.
• Make a level that requires undoing at all.
• In case you haven't yet played the game, Raemon's Exercise: Planmaking, Surprise Anticipation, and "Baba is You".

This sounds too high effort, but can I try to solve the level you made?

Yes, but you wouldn't be able to experience the challenge unspoiled after. Here is the level code:

I completed the challenge. Now what?

Post your level here if you want! (I'd be curious to see it)

But do you have an even harder challenge?

Yes. Find some combination of rules and objects which is probabilistically guaranteed to have an intended effect on an arbitrarily large but non-uniform baba gridworld. Assume the baba gridworld contains a computational clone of yourself near the location of the structure; the 'intended effect' refers to what this clone thinks would be best.