Let's assume a planet is taken over by two groups: The Necromorphs take one half and infest the area, the Xenomorphs take the other half and infest the area. The two are bound to meet eventually, and it will be bloody. Who would win that fight?

Good question.

I think once the planet is entirely infested, the Xenomorphs have the upper hand. Provided they can still incubate a Necromorph's host. I think the acid would make it impossible for the Necromorphs to do much with the slain Xenomorphs. I think it really comes down to whatever the original life forms were on said planet. Though my dead space knowledge is a little lacking. The Necromorphs might have traits I don't know about. have they proven to be acid resistant?

Good question.

I think once the planet is entirely infested, the Xenomorphs have the upper hand. Provided they can still incubate a Necromorph's host. I think the acid would make it impossible for the Necromorphs to do much with the slain Xenomorphs. I think it really comes down to whatever the original life forms were on said planet. Though my dead space knowledge is a little lacking. The Necromorphs might have traits I don't know about. have they proven to be acid resistant?

They've proven to be resistant to plasma in some occasions. Slain Xenos are easy to deal with, acid blood or no acid blood, as the necromorph virus is spread through the Marker into corpses, though it can also be given directly. We'd have to assume a Marker or two is on the planet they're on for there to be any Necromorphs.

As for incubation...it could happen, if the Chestburster doesn't feed off the host's nutrients. However it might come out infected.

well, now i'm almost leaning towards the necros coming out on top. Though in the zenos defense, they have proven to be ferociously intelligent. I can see them very quickly discovering ways to deal with the virus spreading among their own kind.

Maybe we should take a closer look at their abilities? The xenos are fast and intelligent, while the necros are durable and can fight with psychological warfare. I wonder if xenos can get hallucinations?

Xenos are controlled telepathically by a queen, which could be able to receive hallucinations. This may or may not turn towards Necros favor.

Necros are extremely durable, have impressive adaptive ability, and often work in packs, settling roles between themselves and using their abilities to strategize.

Xenos are also extremely durable, and stealthy. Similarly to the Necros, they work in groups, though more spread out. They strategize at a basic level- like a wolf or, as my friend put it, somewhat like wasps.

Necros can see the neurons in our brains, without ACTUALLY seeing. This means they can hunt any thinking creature, and understand the difference between non-necromorphs who are working against them, and non-necromorphs who are under the affect of the marker.

Xenos have an excellent sense of hearing, as well as being able to sense the heat of creatures, which gives them the advantage in fighting Necros, which produce a large amount of heat when created and retain this heat for a chunk of their natural lives. Xenos can also see eachother, meaning if a Xenos became a Necros, they would quickly come under fire from Xenos.

Physically, the two are the same- fast, strong, capable of withstanding environments that prove lethal to most other creatures.

The two are very similar, only differing in a few places. They can both differentiate from eachother. They have the same strengths. They use the same tactics. The few things the two don't have in common, is their way of reproduction and the Necros ability to turn dead tissue into a large bio-mass that would quickly cover their half of the world.