ibb & obb is on Steam! Isn't that nice? Yes, yes it is nice! The gravity-inverting cooperative puzzle game from Sparpweed took the better part of a year to make its way from PS3 to PC, but it brought with it everything that made the original so great, including both local and online co-op for two players!
The idea behind ibb & obb is to grab a friend and scratch your head over a series of gravity and physics puzzles, all while nabbing shiny diamonds and dealing with enemies. The controls are as simple as walking and jumping, but it's the warped environments that make the game so intriguing. Fuzzy gates instantly flip gravity for the player that jumps through, allowing ibb to be facing "up" while obb is mirrored below. Crossing the landscape is an exercise in weaving in and out of these portals to pick up momentum and reach the next highest platform. It's all so elegantly simply, but the puzzles will throw your gray matter for a loop.
The Steam version of ibb & obb has all the features from the PS3 release with the added bonus of Steam achievements, trading cards and cloud saving. Because co-op is better that non-co-op, the a special Best Friends Forever Double Pack is available for a deep discount over a single copy (which still supports local co-op, by the way). There's also the option of buying deluxe packs that include copies of the game along with the soundtrack by Kettel.
Source: Store.steampowered.com