Procedurally-generated worlds, in which the computer is able to randomly design an entire area on the fly, are the future of game development.
They already exist in the games of today, of course. Minecraft, for example, procedurally-generates a new game world every time you begin a new game. But Minecraft doesn't look as pretty as this.
These screenshots are from a project by Miguel Cepero called Procedural World. It's not a game in itself, but as he states on his blog, the technology has very gamey applications, like making a "Dwarf Fortress universe with rich graphics" or a "nextgen Minecraft".
Things are obviously a little rough in spots, as this is a work-in-progress, but what's already been achieved is amazing.
Now, the computer obviously doesn't do everything. The programming has to be done by man. But once it's loaded in, all those sweeping vistas and towering mountain ranges are one-of-a-kind instances, creations of random chance.
Which is probably what makes them so breathtaking. It took billions of years of random events, not the hand of a video game artist, to shape the real world; it's probably for the best we let billions of random events shape our game worlds as well.