Hanabi and Room 25 are the only pure Co-op games as far as I know. Note that for Room 25 "co-op" needs to be selected as the game type (the default is suspicion mode which is a team vs team game).
There are other team vs team games too such as Coup (with "factions" on), Werewolves of Miller Crossing, Secret Moon, and others.
We definitely need more pure co-op games though...