Over is a space-based comic-like RTS game with some MMO features (persistency, commander profile, etc...) It also features customizable fleets and wings. Over is build on a completely custom engine which currently runs on linux and windows.
LxDoom is a version of the classic fps game Doom by id Software.
Specifically, it's an engine for playing Doom levels, based on the source
code released by id Software. It aims to be free, reliable, portable, and
support a wide range of levels.