I have been playing around with the Tiberian Dawn editor lately, i suddenly found that it was possible to create multiplayer missions. Although with a few bugs the ai works really well and the missions can actually be quite challenging. I can't believe nobody thought to implement coop in CnC before, anyway here is a few minutes of gameplay from the map i edited, it's one of the maps from the final mission of the GDI campaign.
C&C1/TD coop playtest (last GDI mission)
If i fix all the bugs on the map which include the obselisks not working for some reason (probably just needs some power plants), the ai resigning when their temple blows up and oddly enough, the enemy makes loads and loads of mcv's and mobile bases, i'll post it in the map section.
As i have said, other than those bugs, the ai works really well, they even tried a chinook tactic on me once which scared the hell out of me.