AI designs its own video game: Angelina creates games using a technique known as cooperative co-evolution. The system separately designs different aspects, or species, of the game. In Space Station Invaders - in which players control a scientist who must fend off rogue robots and invading aliens to escape a space station - the species include the layout of each different level, enemy behaviour and the power-ups that give a player extra abilities. Angelina creates a level by randomly selecting from a list, then scattering enemies and power-ups throughout the level. Enemy movements and combat behaviours are also randomly selected from a list, while the effects of the power-ups are also random.
It then combines the species and simulates a human playing the game to see which designs lead to the most fun or interesting results. For example, levels that are initially hard to complete but get easier through clever use of power-ups are considered fun, while those that are impossible to complete are discarded. Angelina then cross-breeds and mutates the most successful members of each species to evolve a new generation, typically 400 times.