Game design is a very complex field, incorporating a huge number of both artistic and technical specialties. Could a computer design its own games? The answer, surprisingly, is yes – or a qualified yes.
Technically, computers already create many parts of the video games that you enjoy. It’s called procedural content generation. Computers can fill in certain parts of a game on their own, based on certain rules, to avoid making the programmer do everything by hand.
Most procedural content generation is pretty formulaic. For example, a computer might procedurally generate textures. Or a Roguelike game, given some rules about the size of rooms and what monsters might spawn in them, might randomly generate rooms and randomly place monsters. (Minecraft and many other games randomly generate terrain, too.) Computers can use fractals and other computer graphics rules to make settings full of trees, mountains, and other natural forms which all look detailed and different from each other, instead of making a human artist manually paint absolutely everything.
Procedural generation can be more complex than this go. For example, there’s the Director AI in Left 4 Dead which not only creates levels but adjusts their difficulty, based on the players’ current state, to keep the pace of the game exciting. And difficulty/pace is only one of many variables that a computer could use to guide its decisions, making them, arguably, artistic decisions, rather than random/meaningless ones.
So much for generating parts of games, but could a computer design a whole game? Arguably, yes. One big project in this vein is Michael Cook’s ANGELINA, which handles everything from level design to a game’s aesthetics and graphics to generating new game mechanics to make playable games. Whether or not people want to play these games is another question – but it should be noted that ANGELINA has taken part in game design competitions with humans, and was not the worst in the bunch.
Video games are very much not my thing, but if you want to know more about computers that design their own games, you can start with Michael Cook’s blog; a lot of other relevant researchers in that field are linked to from there.