As it turns out, Rage has a co-op mode. In this mission, vile fiends have placed bombs throughout Wellspring in an attempt to destroy what's left of the water supply.
There's an awful lot of running, gunning, and reloading. Seriously, whoever was playing reloads as much as I do -- which is to say at all times. With the combo system and separate point totals per individual player, this could go from friendly fun to mean-spirited name calling in an instant.