Natural Selection 2 is a stand-alone video game available through Steam that is a revamped version of the Half-Life mod. The game features two unique sides, alien and marine, each with their own strengths and weaknesses. Players can customize their characters to suit their playstyle or join one of several premade classes. Natural Selection 2 also includes a variety of maps that are designed for intense 5v5 battles between the two opposing teams. The game has been praised for its focus on teamplay and strategy, as well as its excellent visuals and sound design.