SuperTuxKart

It's weird I haven't mentioned this one before, because SuperTuxKart is one of my favorites, and an excellent and very impressive project. Akin to the iconic and endlessly fun Mario Kart, TuxKart has several open source mascots challenging each other in racing competitions around all sorts of colorful tracks and environments. Game control is great; everything from handling to skidding feels good and robust. Track and character design is awesome, and seeing Tux, Gnu, Wilber, Pidgin and other foss mascots drive past you fully animated is cool to see. Further, SuperTuxKart has a story mode, split-screen multiplayer, an addon-archive and loads of included content just waiting to be discovered, all greatly polished. SuperTuxKart is already a very good game, but a lot of great features are still on the way to look forward to, such as network play and better graphic effects. This will without a doubt be a game to define great open source software in the future, something that can only be said about a few of the games mentioned here. Playing Super Tux Kart, especially with friends, is a joy and it really deserves a try!