Metal Slug on CRACK!!
And, trust me, that's a very good thing.
I rented this for PS/2 the other day, didn't expect all too much of it, but it turned out to be AMAZING. Best game released for PS/2 in quite a long time, and it had something I was really trying to find on the Playstation in past months - a two-player co-operative game that didn't involve RPG elements. Thank you, everyone involved, for bringing a wide smile to my face.
FBI, giant killer robots, all of the humor (the 'Nothing to See Here' sign, followed by stealing Fat Kid's ice cream cone... Classic!), and the little things like being able to roll, or ride your fellow Hominid, make this game one of the best I've ever played.