spaceBOUND is described as 'brutally challenging solo or co-op puzzle-platformer. Players control two astronauts who must overcome deadly obstacles while solving physics-based puzzles in a zero-gravity environment'. There are more than 25 games similar to spaceBOUND for a variety of platforms, including Windows, Mac, Linux, Android and iPhone. The best alternative is Limbo. It's not free, so if you're looking for a free alternative, you could try SuperTux or Mari0. Other spaceBOUND like games are Hollow Knight (Paid), Braid (Paid), Ori and the Blind Forest (Paid) and Alex the Allegator (Free, Open Source).
Alex the Allegator is a series of games that I, Johan Peitz, usually use for game coding challenges like Speedhack and Ludumdare. Whilst most of my games reside on Free Lunch Design, this is the place for the Alex' series and the even the source for these games. Let's go! Represent entire series of Alex the Allegator games including Alex the Allegator 1, 2, 3, and 4.
Super Meat Boy is a platform game developed by Team Meat and is the successor to Edmund McMillen's and Jonathan McEntee's flash game, Meat Boy, originally released on the Newgrounds website in October 2008.