You guys have some great feedback. I assumed many fans of GTA probably thought of something like this before. It definitely would take too much time to create a game like this the traditional way. Some brilliant minds would have to create some software that could create realistic environments in terms of geography, climate, plantlife, etc. I could imagine inputting the size of the planet, where it is relative to the sun etc. Maybe you could even just tell the software what type of planet you want created, and the software would do all the work. For example, you could ask for a big gas planet, a few extreme smaller rocky planets, an icy planet, and of course, a nice living habitable planet. The software would then create a ready made solar system with working planetary orbits. Scientists are using similar software like this now, to try to understand how all kinds of stuff happens in our universe. I really believe a software like this will be developed at some time in the future for gaming applications. Somebody is always creating some software to make developing easier. As tech gets better, developers are able to do more, but doing more takes longer unless there is a way to make much faster. Just like hair in games. I bet one day every individual hair on a characters head will be perfectly modeled and have it's own physics, but who would want that job? The answer is always automation.
R* would then only have to worry about the cities, people, story and other traditional aspects of the game. It would still be a lot of work, but I think they could get it done in a few years. This would be a huge world, but nowhere close to the size of our planet, or even our moon. The surface area of our moon is 37.9 million square km, which is smaller than the surface area of Asia at 44.4 million square km. Those our really epic numbers, but I wonder if we were judging on a scale of "Mario Galaxy planet - an actual planet", what Red Dead's map would look like wrapped around a globe. Or how about Just Cause 2? Or even better Fuel? Would they look more like Mario Galaxy's Planets, or would they resemble something closer to our earth?