The Bad Guys have taken over a building in a Generic American City, and they’ve kidnapped some Innocent Scientists and forced them to genetically engineer Evil Mutated Monsters as part of a fiendish plan for World Domination. But the creations have turned on their creators and escaped, and are running amok inside the building, in an orgy of Death and Destruction. It’s up to you, the Good Guys, to recapture the building, rescue the Innocent Scientists, and kill all the Bad Guys and Evil Mutated Monsters.
Very fun mod! I played it on Mac no problem. It's pretty short but fans of OP4 squad-based gameplay will love it! You get to take your little gang - a medic, engineer, and gasmask shotgunner - throughout the entire mod. There's a good selection of enemies to fight: enemy HECU marines, black ops, HECU zombies, and a small assortment of Xen and Race X aliens - there's also a great helicopter boss battle. Overall very fun little mod, it took me about 20 minutes to beat.