We've been talking about this for a quite a while now since it's reveal last year, and I'm honestly surprised that literally no one posted a thread about it yet.
Basically, it's an adventure-puzzle game set in a small, compact world... where you play as a mouse. There's not much action to it, but that's not the point: the game is about exploring, solving puzzles, etc. (Also; if hostile mobs detect you, your basically dead; there's a heavy emphasis on stealth).