Plot: Armagetron Advanced is a multiplayer snake game in 3D based on the light cycle sequence from the film Tron. It is available for Linux, macOS, Microsoft Windows, AmigaOS 4 and OpenBSD as free and open-source software. Wikipedia
Plot: Liquid War is an open source multi-player action game based on particle flow mechanic. Thomas Colcombet developed the core concept and the original shortest path algorithm, the software was programmed by Christian Mauduit. Liquid War 6 is a GNU package distributed as free software and part of the GNU...
Plot: kiki the nano bot is a puzzle game, a mixture of the games Sokoban and Kula World. It is available for Microsoft Windows, Linux, FreeBSD and Mac OS X. Wikipedia