Devs get lazy and think multiplayer can save a game. But it doesn't. Not if the entire game is bad to begin with. Give the game about a month, maybe abit, less and the game will be deserted online. Multiplayer can make a game last years if done right. *Cough AVP2* sure COD wasn't a problem then. But if a game has fun adicting multiplayer people are gonna stick around and continue to play it so long as theres reason to. Even something as basic as a leaderboard and 50 or so rank ups give people to keep playing, especially if theres a nice reward at the end of it all.
This game could of been fine without the singleplayer aspect and instead stay a multiplayer player team based shooter ala left 4 dead. Your your simple objective is to get to the other end of the level alive against eight or so alien players. Anyone played that steam game "Swarm" Gameplay like that where you place turrets and wield doors and stuff.