SuperTuxKart - 3D arcade-style MK-like kart racing game
Mari0 - What happens when you mash Super Mario Bros. and Portal together?
TrackMania - The most popular online PC racing game.
SuperTux - SuperTux is a classic 2D jump'n run sidescroller game in a style similar to the original Super...
Speed Dreams - Speed Dreams is a 3d cross-platform, open source motorsport simulation and racing game.
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.