Portal: Revolution is a modified version of Portals 2 that tells a new story with new characters, adding to Aperature's deep lore and fascinating gameplay concepts. The characters are almost as funny as the ones in the original games (which is a really impressive feat), the new mechanics mesh with the old ones in fantastic ways, and the puzzles themselves are fun and interesting. The only complaint I could muster is that the difficulty of the puzzles are inconsistent throughout the game, with an odd progression, but the puzzles themselves are, like I said, fantastic. If you love the Portals series, then ABSOLUTELY 100% check this game out. It's free on Steam, and gave me a few afternoons of fun.