The Nuke
Once you have the sentries set up, return to the laptop in the basement of the large building and deposit the final $1000 to get the attack chopper on its way. This will also help keep the aliens off your back as you try to make your way to the start.
Return to the bomb, and to arm it, each of the players will need to hit the X/O button simultaneously. If you have boosters, throw them down to give you some additional speed, as well switch to your pistols as if they are upgraded at all, you will be able to run faster with them equipped.
Now you will have 4 minutes to return to the helicopter, so get moving! As soon as the bomb is armed, aliens will start appearing and attacking. Keep running and only stop to kill those that are in your way. Once you reach the city entrance, a meteor will block the path between the buildings and you will have to make a stand and fight off all the enemies that show up. Throw down your ammo and armor and stand your ground until the meteor blows apart and you can pass.
Once you can, keep running to the exit of the city to the motel and there will be another meteor blocking the road. Again, make a stand with all you have and take out the rush of enemies there until this meteor blows apart as well. Now you just need to run to the very first hive location and the helicopter will be hovering above a circle of lights.
As soon as all 4 players—or whoever is left alive--enters the circle, you will board the chopper and take off, completing the game. As a bonus, if you make it to the chopper with over a minute and thirty seconds left on the timer you will earn yourself an extra achievement/trophy for being so speedy.
