The co-op mode for this game in unbearable. I played this with one of my friends and we had the best maze possbile with leveled up towers. But guest what! They send either 500 speedy units that you can only kill a few or they said a about 5 giant units with around 10,000,000 hp. I thinking I got this since I upgraded my sniper rifle and the damage ampfing square to the max level doing around 1 million damage per shot. But guest what! There big monsters just laugh at the damage and just go on slowly to your base. There is no stratgeay when all you do is sit there following the monsters shooting at them. I feel like all the towers don't do anything but add a little damage here and there even though they are full upgraded. The anti air towers are the only good towers. I can tell that the multiplayer was meant for 4 players and if you got anything less than that you're going to lose.
The sad thing is your not just going to be killed but your going to be absolutely destroyed. They would kill us and there would still be about 50 more units still alive. To conclude this, I think Orcs Must Die! 2 did the tower defense with fps better. You felt like you could win, you felt like with one more try you could beat the enemy; in this game all I felt like was that the game was just being really cheap and unfair. I just started and the game expected prefection. Although I heard the single player was better. But again, surprise surprise, the levels are so BORING AND LONG. I couldn't recommend this.