Puzzle game where you push blocks around. Blocks with words can be pushed together to change game behavior. For example on a level with Baba, Is, and You blocks together let you control your character (your character is named Baba). But if you push a block that says Door in front of the Is and You blocks you will suddenly control the doors instead of Baba. It's a really cool concept and the levels get extremely imaginative. And also difficult
It's been on PC for years. It's a puzzle game where you push tiles around to form simple statements, and those statements affect the rules of the level you're on.