OddPlanet ($0.99 > FREE)
The game currently has only one episode which you can complete in less than an hour. But still worth checking out. The dark atmosphere (headphones recommended) is really great. I hope the game will get updates with new episodes, at least they are promised when you complete the first episode.
Favorites: The Quest Gold + expansions, Mission Europa Collectors Edition, Ascension, Jet Car Stunts 2, Junk Jack X, King of Dragon Pass, Kingturn series, Mecho Wars HD, Mini Dash, Mos Speedrun, Ravenmark, Sonic series, Fall of Angels, Highborn, Solomonís Keep / Boneyard, pixel art games, remakes and ports of classic games.