Thank you to everyone who's tried out the game! Here are some more changes based on your feedback:

* There's now a funny error message for interacting with the mirror twice. (reported by two people)

* Mouse pathfinding now works if the player is on an occupied tile (reported by one person)

* The steel wall is now an x2 wall. This is objectively funny. Also, I implemented multiplier-walls and multiplier-doors in case I ever needed those. (suggested by two people)

* Picking up green things now leaves behind residue on the ground, so in-progress screenshots give a better indicator of the route taken. (suggested by one person)

I would like to add meta-undo (undo to just before you last used a Greenality) but thinking about how to implement it makes my brain wibbly.  See also: Save states, replays, level editor.  If I ever figure any of this out, you'll be the first to know!

EDIT: v1.2.1: Fixed that using the warp wings overrode an important ending related message. (reported by one person)