Sure.
For co-op, we expect each game to be "hosted" in some way and letting other people log in. In our wildest dreams, we would host your game on our servers (perhaps for a modest fee to cover hosting costs), but we want you to be able to host your own game on your computer if you want, or buy the server yourself. When you get a bunch of people in game, they would all have joint-control over your city, all working toward growing it. Maybe as the game owner you can give out certain controls (e.g. your girlfriend can build anything, anywhere, but your scumbag, mooching cousin can only build in this area, using these resources). So it's like a bunch of people all helping to play the same game.
I don't really consider this "co-op", but there's also the idea of integrating your social network into the game via resource sharing and assists. For example, I should be able to send you 100 wood and 100 stone to get you started. Or if there's a goblin camp that's threatening you, maybe you can invite my band of high-level adventurers into your game to clear them out for you. Again, this really works well with the hosted service (how do I invite you into my game if my computer is off? hmm.).
For PvP, the model we're most excited about is an asynchronous model where people can invade a copy of your city. For example, if you've built the most bad-ass, defensive structure with traps, deadfalls, and dragons guarding a treasure box in the middle, I should be able to download that map and play the role of the invader trying to get at it. We could have leader boards were people could rate maps (according to challenge level, enjoyment factor, etc.) and success rate (e.g. 85% of people who try to invade this keep have failed) to make it easy to find the really awesome maps. This is really where moddabilty can shine, IMO, since people can create these maps with all sorts of unique challenges (e.g. a Game of Thrones or LotR map) complete with their own little plot lines or magic items unique to them.
There's another mode of PvP where we would essentially take your map and the other guys map and stitch them together. Sort of lifting your city up and putting it down right next to theirs. That would play out like an RTS game (like Starcraft) resuming right from the middle after the build-up stage. I think this would be completely awesome, but is a stretch. If I were playing with a lot of custom mods and you were playing with an entirely different set of mods, we somehow have to combine the mods together, which might be really difficult. We're thinking of ways of how to accomplish this, but it might not be technically feasible, at least not at the outset.
These are all just ideas. One of the reasons we're doing the Kickstarter so far in advance of the beta is so we can see what ideas most resonate with people and work on making those a reality. We really want to engage the community up-front to make sure they love the game as much as we do on release.
