In theory, we could do something insane like 256 players or even more. Since this is turn-based, there is no ongoing data-transfer between players except for once-per-second heartbeat messages. The only main messages happen when players actually take some action, or when the AI on the host gives orders for what the people on the map are going to do, and what resources are produced, etc. And those messages are pretty reasonably small; compared to something like AI War or the Valley games, the amount of bandwidth required is pretty slight.
In reality, I think a game with 256 players would be utter pandemonium and not fun at all. The worlds would also get untenably large to where you couldn't keep track of anything, and doing the initial transfer to clients of such a large world (and doing savegames of it) would be a much higher load. Still probably better than AI War or Valley 2, come to think, but I've not calculated it out for sure. Compression makes a big difference. Anyway, I don't think that would be very fun.
Most likely we'd restrict it to something like 8 players so that we're not trying to balance super-edge-cases out there, but I'm not positive on that number. That's just what I'm thinking at the moment. I should also stress that we've not yet tested the co-op at all, though we're obviously designing around it and the multiplayer model from Valley 2 is in-place under the hood. But after private alpha starts, one of my things to do is going to be getting all the bugs cleaned out of the multiplayer; that's quicker to do all at once at the end with a game like this. There's a pretty limited number of types of messages to pass around (like AI War or Tidalis), unlike the Valley games.
