Rise of the Zombies

A brawler rather than a shooter: the city is overrun, you have two fists, and the zombies arrive in waves that never officially end. Rise of the Zombies pays gold for every one you put down, and that gold goes into three things — how hard you hit, how fast you move, how much you can take — which is the whole progression. The undead get tougher as the waves climb, so the run turns into a question of whether your upgrades are outpacing them. They usually are not, and that is rather the point.