Level 20 still haunts me.
I beat it once and yet when I come back to it, there's a lingering air of impossibility about the thing. Whoever designed that one could have a lucrative career in creating torments.
This is a collaborative game made by members of the Thinky Puzzle Games Discord server, from March 31st to July 31st. The format was an "exquisite corpse" style, where each person adds on a little bit (a level, a mechanic, and/or polish), and then passes it on.
Participants: (in order of participation, but not in order of levels) (37 total)
Henrique de Lima
The exported game uses pancelor's level select fork of Puzzlescript. The "hack" link will take you to the game's original source code, without the level select functionality.
You can also play the previous collaborative game, What Gophers Go For!