Just more places and things to do. Nice and simple, but huge effect. The original concept art had huge potentially sweet areas (swamps in Chicago and some moss covered city, a really cool looking shot of a base in some frozen moon). I'd also love to see more passive areas, whet fighting isn't everything. The raid covered this well with the gorgon stealth bit and the jumping puzzle. ( an actual maze bit in a busted up building would be a nice break and not all that hard to do considering the games theme