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Before Alien, there was ALIENS: EARTH WAR
www.clik.to/alienearthwar
personally i think it would be more interesting to see something done more in the stye of Alien than the cheesy Aliens rip-off action blockbusters that they keep trying to write.
i think it would be cool for the predator species to be the hunted, they have met their match with the Alien species. it would be interesting to see the dynamics of the two species fighting because they are pretty much even matched if you take away all the predators technology. otherwise it would be pretty unfair because they are so advanced. mabey have a predator crash land on the alien homeworld and he has next to no weapons so he has to fight the aliens solo or something, i dont know.
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i'll swallow your soul!
The Human space race takes a gigantic leap forward. Soon, we are colonizing just about every planet we come across. On one such planet, a batch of unknown eggs are collected and taken aboard a research vessel.
As this ship continues it's journey through space, It's next stop is a planet used by the predator species as a ritual hunting ground. When the humans land here, the predators begin hunting them.
However, as the humans are getting killed, the eggs aboard the ship hatch, releasing aliens upon the planet. These aliens begin hunting humans and predators alike.
Now, the only chance of survival for both species is to combine their forces...If they don't kill eachother first.
That's what I'd do anyway.
My Two Bits,
Bread
The predators: Since this is the ritual hunting ground, these would be the inexperienced hunters. Most likely hunting in packs. They also would not have such advanced weaponry as the shoulder cannon. However, they would definately have the traditional weaponry such as the expanding spear, disc blade, etc.
The Humans: Some would be space marines, armed with machine guns. Others would be defenseless scientists. Some may even be androids. Who knows. They are easy prey for both the predators and aliens.
The Aliens: These acid spitting fiends fear nothing. They will kill anything and everything in their way. This includes predators.
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What should happen:
First - The predators begin killing the humans.
Second - The aliens begin killing humans and predators.
Third - The predators make contact with the humans. A truce is made. The deal: Help eliminate the aliens, the humans may leave peacefully.
Fourth - A small team of humans and predators take down the queen and save the planet. In retaliation, the predators vow to hunt down every last one of the aliens. This is to honor the countless dead that have been taken by the aliens.
The humans leave, the predators go hunting. The end. Or is it?
My Two Bits,
Bread
anyway, just an opinion. 
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"I am Mars, the god of War, and i'll cut you down".
ok well not so huge , but close .
All times are ET (US)