Populous

You play a god, gaming against other gods in a celestial game of conquest. To win, you must help your chosen people take over the world and wipe out the vermin who worship that other god. Each god starts out with a single human, dumped into the middle of the wilderness. Sometimes there is inhabitable land in sight, sometimes not. To get win, you must change the landscape, creating flat land for your followers to build on. The more followers you have you have, the more powerful you will be, so take care of them. Build as fast as you can, because the other god is doing the same.