Well, everyone can leave any type of enemy free for interpretation. For example: I see the monsters as the Locust from Gears of War, the aliens as the aliens from the Alien movies, the zombies from any movie and the ghosts as the guys from FEAR.TheNamlessGuy said:The most logical choice would be Monsters, as:
The Zombies wouldn't stop coming, as you said
The Aliens would blast you to a pile of Goo ([Fallout 3 joke]unless you open the console and type TGM[/fallout 3 joke]
The Robots would find some way to self repair and repair each other, resulting in them never dieing (Unless the batteries run dry)
The Ghosts would need special equipment. Do you have a proton pack lying around? I sure as hell don't!
Plan 9 From Outer Space I think, a.k.a 'the worst movie ever made'War Penguin said:Aliens. They can create zombies so you know they're trouble. (that's a reference to a movie but I don't know which one)