This isn't a fresh co-op experience. Aliens vs. Predator, the original PC/Mac version, did this. . . by accident. In a mode called "species deathmatch," set with balanced teams, you'd get 4v1. . . or 4v1v6 or somesuch when all three species were in a map. It was a blast. . . when it worked.
So there's room to do it better. AvP was fraught with bugs and balance issues (bad marine players = dead, good marine players = gods, several of the predator weapons had to be regularly banned), but it already played faster than what we're seeing here.
But, good or bad, this has been done, and been done in a playable fashion.
It is not inspiring that there is no evidence that monster has few mobility advantages over the ranged enemies. (Being able to get up higher than the enemy isn't sufficient.)