A multiplayer game doesn't just have to grab the attention of its players with good design, it has to keep enough of them involved for anyone to bother playing at all. At Lost Garden, game developer Dan Cook, known for puzzle game Triple Town and dogfighting game SteamBirds, has laid out an exhaustive guide to multiplayer design, breaking down the core concepts and techniques behind creating something that people will want to come back to. It's very, very long, but it's well worth the read, even if you've never really thought about actually making a game.