Knytt Underground, the latest platformer from Nicklas "Nifflas" Nygren, will be released on PS3 and Vita via PSN tomorrow in North America. Europe will have to wait until December 21, but will have access to it free with PlayStation Plus, which more than makes up for the brief wait. It's also coming to PC, and to Steam if it gets enough Greenlight support.
Knytt Underground consists of more than 1,800 rooms, through which you'll run, jump, grapple, and bounce. The release date announcement also promises "multiple story-driven quests" within these interconnected rooms.