Rubicon X is a free, cross platform, first person shooter that continues the story of Bungie’s Marathon Trilogy. First released as Marathon: Rubicon in 2001, Rubicon X is a complete overhaul of the original. It features all new high-resolution artwork, new and updated maps, and enough surprises to feel like a whole new game.

Pros: Rubicon X uses the Aleph One engine to provide detailed high-resolution textures with OpenGL-powered lighting and fog effects, and features “a nonlinear plotline that can be traversed in any number of ways, featuring different endings based upon a player’s choices over the course of the game.” Rubicon X is a cross-platform game for Mac, Windows, and Linux.

Cons: None significant.