A game with a multiplayer mode allows multiple people to play the game together, whether by cooperating on certain goals or by competing against each other. Some games allow local multiplayer, for example, by using split screen and multiple controllers (and early PC games used different parts of the keyboard to substitute controllers). Some games allow multiplayer through a local network. Most modern games, though, use online multiplayer mode via the internet. The online multiplayer requires constant internet access. The number of players the game allows in multiplayer modes may vary from two, usually in local multiplayer, to an indefinite number of people in shared worlds of online games. In most games, multiplayer does not rule out the existence of AI-controlled participants.