One idea I had was to have the player switching between characters, a marine and an civilian, with the marine having to fight their way pass their alien encounter to rescue the civilian, who can then assist the marines by getting into places they can't and opening up areas and objectives that brute force can't. Also have a marine isolated on his own, with limited ammo and multiple hostiles around him which would tear him apart if he so much as fires off a burst, requiring him to be tactical in order to get out safely. We can still have stand offs and last stands where multiple marines are present, but the main focus should be trying not to attract unnecessary attention that would waste your ammo. And some marine rescue mission objects or bonus objectives would be brilliant. There were a couple of survivors in A:I that had the potential to be saved if the game allowed for it, instead of just being alien bait if it happens to drop down in that area looking for you. Really pissed me off since the exit was just right beside them.