Having recently bought the game and beaten it, I'm disappointed the game didn't have much rewards to offer beyond the knife tricks minigame. So if you could have added more content, what would it have been?
First, I'd have made it possible upon beating the game to restart with any of the marines you recruited, all with dialogue of their own. If you chose to have say, Cuchillos, instead of Paulson, then the latter could be found at Cuchillos' location if you lost a marine and wanted to have him back on your team.
Secondly, the likes of Vasquez, Hudson, Hicks etc as hidden characters, also with dialogue of their own. Or as alternate skins for some of the characters.
An Alien-centric scenario.
You don't have to exclusively mention extra content. You can also mention what you would have changed. In my case, I'd have kept every marines' designs individualized during gameplay instead of palette swapping them all.
Make your own marine.
*Dusts off topic*
Wouldn't mind an Alien bonus mission- where you get to butcher everything in your path. Wishful thinking...heh ::)
I'd have really liked another saving slot.
I'd have loved a longer single player story personally. I really enjoyed the game - was very surprised at how enjoyable it was and the short campaign was my biggest gripe.