Choosing our characters required some thought. There are quite a few, each offering different skills and strengths that affect play, from unique weapon skills to better stats for hand to hand combat. Don't misunderstand: we didn't see a whole lot of difference between the different characters overall, but it was fun to spend some time deciding.
Once we picked our character, we were off and running. We immediately got sent to accomplish various tasks (something about stopping a dimensional portal that the aliens are coming through...) and along the way we ran into many, many, many different types of aliens, from four legged spidery-like ones to towering monsters with razor-blade arms. And guess what? They all had to go.
There are dozens of weapons offering different ways to kill the aliens. Handguns, shotguns, grenades- you can freeze them, broil them, vaporize them and of course, shoot them. The environment can be used- fuel barrels can be shot at so that they explode, or shooting out lights in hallways to darken them. We were glad to see that we got a flashlight and a gun this time.
There's a multiplayer mode for co-op play that offers an online deathmatch arena to challenge other players in, as well as a survival mode, a last-man-standing event where we got awarded with better weapons and armor the more waves of aliens we lived through.