I thought of an interesting (IMO) game idea, which probably would work as either an adventure game, or an RPG: You create a character, and immediatly at the beginning you are given a time machine, and can go back to any period in history, and change something in the past, and return to the future, and see what has changed. The game would obviously have more or less limitless senarios, so it would probably utilize a varible system. I'm guessing a game of this size and grandeur wouldn't be possible for a long time, at least not in the scale I envision. Now this game may seem a little too vast, but imagine what the world would be like today had Hitler never existed? Thomas Edison? Caeser? Or if the Earth had moved ever so slightly to the side for a few minutes 65 million years ago, and the meteor never wiped out the dinosaurs?