Chapter Master is an unofficial fan project where the player commands a Chapter, an autonomous, largely self-sufficient unit, of Space Marines to defend the Imperium of Mankind from various alien and human threats. The player must contend with enemy forces, the dangers of space travel, and the internal politics of the empire to keep their chapter alive and win glory to their name.

The game is heavily inspired by Master of Orion 2, drawn from a 2011 thread of speculation on 4chan.

The most current version of the game can be downloaded from the thread on Bay12 forums.