With a games machine, a player can enjoy games either fighting against another player or fighting together with another player to overcome a common enemy. In such a case, first and second game controllers could be connected to a single games machine, for example, and first and second players could manipulate the first and second game controllers to play such a combat or allied-combat game.
On the other hand, it is sometimes necessary for a games machine to allow a player to enjoy a game alone (single-player mode), in which case the player can fight against a computer player or fight together with a computer player to overcome a common enemy.
However, a computer player can often act only as determined previously by a game program or the like, so it lacks opposition as a combat opponent and is not supportive as an allied partner. That is why games machines up until the present have a problem in that, although such games are enjoyable in multiple-player mode, it is difficult to enjoy them in single-player mode.
This invention was devised in the light of this technical problem and has as its objective the provision of an image synthesis method, games machine, and information storage medium that make it possible to provide thoroughly enjoyable games, even when only one person is playing, for example.