WarMUX - the WAR of Mascots from UniX - allows you to pit your favourite software mascots against in each other as they fight with grenades, baseball bats, dynamite and assorted other weapons in this free open-source Worms clone.
Launch the program and you get to choose which team you're on: Firefox, Thunderbird, Gnu, PHP, SuSE and so on, each of which of course is headed by the appropriate mascot. Pick a map, and you're off, as the gameplay allows you to take turns at navigating your way around the 2D scenery and destroying your enemies.
The graphics are on the basic side, but this does at least mean you can play the game on just about any hardware, and still be entertained.
And there are plenty of customisations to keep the game fresh and interesting. So you might adjust the strength of gravity before you start a new game, for instance. And you can play a human opponent across your network, as well as the computer on your own PC.