The deathmatch in Spelunky HD is freaking ridiculous. I totally love it.
It’s like a bite-sized Smash Bros., in that its pure insanity with a layer of skill that pervades through it all. Bad players can win by luck every now and then, but good players will usually dominate.
In general, the multiplayer in Spelunky is wonderful. The degree of griefing and trolling in the co-op is spectacular. And then every now and then you buckle down and actually make progress, until someone accidentally hits someone with a rock, and then another person kills the damsel while the ghost pisses off a shopkeeper, leading everyone to their certain doom.