Sirus Gaming: Serious Sam 4 is an action first-person shooter game made by Croteam. It is the fourth main entry to the franchise and a prequel to its predecessor, Serious Sam 3. You play as the man himself, Sam Serious Stone, as he travels to different places of the world in search of the Holy Grail, as an effort to stop an alien occupation from completely overtaking the Earth.

Source: N4G PC Serious Sam 4 Review | Sirus Gaming