Eradicate the alien infestation and complete the mission objective.
Use the arrow keys or the WASD to move around.
Use the mouse to aim and fire. The green dot to determines the perfect moment to fire. Try to aim for the head.
R to reload.
Press space to open a door.
Press 1,2,3 to select weapons.
4,5,6 to use special skills.
Press C to go to the upgrade screen when you have levelled up.
Press M to use a medikit.
Alien infestation is often a bad thing and this time is no exception. They are all over the place and seem to be in a permanent foul mood. There is a positive side to all this however, you have a very big gun.
It is up to you to end their presence. Complete the mission and make sure to blast every last one of them into a green pile of muck.