Multiplayer is definitely possible, but it opens up a few issues that we're not really happy dealing with yet. After a few games, definitely.

The first multiplayer games we do will probably be something far less twitchy, because lag between countries won't be so much of a problem (we simply can't afford to go and rent servers in many different countries, which we'd have to do for a twitch game).

But something like a multiplayer strategy game, we could just use EC2 to spawn instances to handle it. I'm not sure whether we'd make a profit on the traffic at the time that they're actually playing the multiplayer games (it depends how many people per server can be hosted), but I'm willing to be that it would still be worth it all round.