If you don't know you can download an offline demo of Neocron. It was definitely different than AO. I assume I was doing something like a mission, and it was exactly like a single player game. If you ever played System Shock 2 it was exactly like that (even has Grav Shafts), but with NPC's on your side. I didn't finish it because it froze but it's definitely worth a look. It should be interesting to see how it will work in a massively online world.