Natural Selection 2 is a standalone immersive, online FPS that pits aliens against humans in a strategic and action-packed struggle for survival. Two teams of up to 16 players face off with unique abilities in dynamic, evolving environments that change as you play. Watch spreading alien infestation deform hallways, and then use a flamethrower to clear it. Cut the power to disable marine structures or weld a loading door shut for defense. No matter what side you choose, you’ll never play the same game twice.

The original Natural Selection was downloaded more than 2 million times and grew to be the most popular independent Half-Life mod.