What retro FPS has good co-op?
I played through Duke 3D with my friend but it wasn't as fun as I was hoping. It felt like more of a singleplayer game with co-op tacked on.
Coop is pretty arse in 90's FPS. Some Doom wads would be good for it but only using modern rules. Classic coop involves either playing levels easy enough on single player becoming really boring with more than one or hard levels where you die and since ammo doesn't respawn you are stuck with the peashooter forever.
Just as boring whether it's easy or hard.
Honestly I feel that Serious Sam is the first FPS ever to get coop right.