Aliens a *LOT* faster but with less health and a better AI, and no friggin AI-teammates, and no dude yelling in your ear every second. No humans as enemies, or at least a lot less of them. That'd be a start.
I guess they could have mixed things up with a mode that has 3 teams: a Xenomorph team, a marines team, and a weyland-yutani team, all operating at cross purposes. Hell they could even have multiple objectives.
Marines: Destroy eggs/queen (in a cargo container), escape. Xenomorphs: Smash controls or otherwise free their queen and overwhelm the hangar (no escape, no safe place for reinforcements/rescue ships to land!) WY: Protect the eggs/queen, protect scientists (or something).
Or there could be a map like the one I envisioned for AvP, but modified for the absence of Predators: A multi story building with lots of vents, etc, with the marine spawn point on the roof.
Just below the roof is a control room where one can turn on/enable say... 2 of 3 things.
1: Sentry guns at certain locations
2: Electric fences (or something similar)
3: Sealing blast doors and/or vents
.. but only once the power is turned on.
The basement would basically be a killing zone for the xenomorphs (and a deathtrap for marines) where there is a switch to turn power on.
Also, melee feels like it has no weight to it, which is bad for marines and really really bad for aliens.
Reign of Dragons referral code H3JC7GR http://www.gamefaqs.com/boards/261-politics/59182173