Your favorites, the artificial intelligences Durandal and Tycho, make constant appearances, as do some new characters, to provide hints and direction. New imagery and plot aside, though, the basic gameplay in Rubicon is much the same as its predecessors. Find a terminal to learn your mission objectives from one of your sarcastic controllers, grab a bunch of weapons and clear a level filled with often familiar, yet vicious aliens while retrieving a computer chip or throwing a few switches. Unlike those that came before it, however, in Rubicon, finishing a level can often be done in two or more ways, as a result of Rubicon's non-linear level design. Divided into two plot lines, Rubicon's level structure is nothing short of unique.
Players leap between the two plot lines, based upon the success or failure of certain missions.
Many new additions make Rubicon delightful. The new Pfhor Shotgun and the Dangi Maser easily stick out as the most fun to use toys in the game, and must be experienced to be fully appreciated. Some of the new Bobs really kick ass, packing assault rifle punch. Unfortunately, there are some rough edges in the game's feel. Many of the levels in the game, while visually adequate, seem almost tedious.