User blog comment:Damac1214/Some Zombie Polls with Some Extinction Polls Thrown in for Good Measure/@comment-3091118-20140119195325/@comment-1263839-20140120212354

Extinction is just facing increasingly large amounts of enemies and backpedaling. Admittedly the finale is kinda exciting (time limits yo), but it doesn't really differentiate itself from Zombies beyond being a linear succession of escorts.