Tesseract is a first-person shooter game focused on instagib deathmatch
and capture-the-flag gameplay as well as cooperative in-game map editing.

Tesseract provides a unique open-source engine derived from Cube 2
Sauerbraten technology but with upgraded modern rendering techniques.
The new rendering features include fully dynamic omnidirectional
shadows, global illumination, HDR lighting, deferred shading,
morphological/temporal/multisample anti-aliasing, and much more.

WWW: http://tesseract.gg/