Viper

Viper is a Snake game for multiple players, up to 3 (in the shareware version) or 6 (registered) - any player may be human or computer controlled. The vipers grow continuously, and can freely worm their way across the playfield in arbitrary directions. Slamming your head into another viper (or yourself) is instant death; the surrounding walls are lethal too, although it's possible to bounce off of them at certain angles.

Players gain points by threading the holes that appear along the worms' bodies as they grow. A player's death scores one point to all living opponents, and speeds up the action (unless playing in 'suicidal mode', where speed is always at max). Once they're all dead, a new round begins - and so on, until somebody wins by reaching the target score. There's also a tournament feature, which lets you record and view statistics and game history for multiple players.