Monster Flood
In Monster Flood, a government research facility has exploded. General Jack Hardman is sent in with his team to assess damage. He lost his entire time to the strange creatures that had mutated from the nuclear fallout. You can't tell if their aliens or zombies or what, but they're coming at you in droves and all you have is your pistol. Pick up weapons along the way that will help you kill more at a time, like the shotgun or the bazooka. It's easier to be accurate shooting up and down than left and right. Finish each wave off so you can advance and destroy the Monster Flood!