From The glTron Homepage:
Remember the incredible Disney film Tron? If so, you'll certainly enjoy this arcade spin-off. glTron is an open source, 3D Tron-style game. The object is simple: each player must drive his or her 'light cycle' along a computer-generated grid and dodge the other racers. To make things interesting, however, each cycle generates a deadly wall of light that blocks off the other cycles--so don't cross your opponent's path! glTron features retro 3D graphics, fast-paced gameplay, great music, and an easy-to-use interface. Play against three friends at the same computer using the A and S keys for player one, the K and L keys for player two, the 5 and 6 keys for player three, and the left and right arrow keys for player four. Press F3 for four-player view mode and get moving. Press F10 to change the Camera Mode - there are three different camera modes.