Blood Frontier (single-player and multi-player first-person shooter)

Blood Frontier is a Free and Open Source game using SDL and OpenGL which 
allows it to be ported to many platforms.  The game is a single- and multi-
player first-person shooter, built as a total conversion of Cube Engine 2, 
which lends itself toward a balanced gameplay, completely at the control of 
map makers, while maintaining a general theme of tactics and low gravity.