Super Meat Boy - Let's start with what's the same: Dr. Fetus is still a jerk, gameplay is super challenging but fair, there are tight controls and great levels and you will die. a lot.
LaTale - LaTale draws heavily from some other 2D side scrolling video games to provide a great fantasy MMORPG world.
Limbo - “Dark, disturbing, yet eerily beautiful, Limbo is a world that deserves to be explored.” Joystiq. “Limbo is as close to perfect at what it does as a game can get.” Destructoid. Buy LIMBO: Special Edition.
Dungeon Fighter Online - Dungeon Fighter Online is a Free-to-play, Massively Multiplayer Online, Role-playing, Action-Adventure, Hack and Slash, and Fighting video game created and published by Neople.
Hollow Knight - Descend into the Dark Venture down into a beautiful, ruined world of insects and heroes
NosTale - NosTale (The Tale of Nomads of Silver Spirit) is a totally free MMORPG that includes simple (but beautiful) graphics and also lots of class options.