Natural Selection

Natural Selection is a Half-Life Modification in which 2 teams—the Aliens and the Marines—try to kill each other off completely. Sounds simple enough—but its much deeper than that. Natural Selection is a very unique blend of RTS and FPS elements. You need to acquire resources for resource nozzles to build more structures, and to become more powerful. If you like First Person Shooters, you'll have a pretty decent time with this game. If you like Real Time Strategy, you'll like it a fair amount. If you like both, this game will occupy unhealthy amounts of your time.