Earth Defense Force: Insect Armageddon

This achievement is fairly straight forward. The target is to kill 5,000 enemies of any type, and all kills count between both campaign and survival. If you are going for completion this will easily be only a stepping stone on the way to the rest of the individual kill achievements.

I personally unlocked this achievement shortly before completing my second playthrough in co-op with very little survival in between just to give an idea of how this achievement really won't take too much time despite how it sounds.