multiplayer support is a far greater attraction than you guys are making it to be. even 2 player games were vastly more engaging than single player games, a simple shooter game like gradius is vastly more entertaining as a joint mission (lifeforce, twinbee)
single player games are fine, but making something that you can share with friends or use to meet new friends is far better.
let's start with something simple. multiplayer asteroids. can it be done?