As a spin-off in the Serious Sam series, it follows Sam "Serious" Stone, who tracks an unidentified enemy through ancient Rome, feudal China and Atlantis, and eliminates the forces the enemy controls to eventually uncover their identity. The player controls Sam through enclosed levels, fighting waves of enemies with an assortment of weapons and, occasionally, vehicles. Defeating enemies is a prerequisite to advance in a level and killing twenty in rapid succession temporarily grants a strength, speed and score boost in a "Super Combo".