That free-to-play game Nintendo is working on is Steel Diver

IGN said:-There is something we’re doing with the Steel Diver idea that I think is going to open things up with that game… It’s going to be very fun. We’re exploring from a perspective of where we can take that from a multiplayer standpoint – it’s going to have this four-player battle mode that I think is going to be very interesting. It’s something that we’re hoping to be able to show relatively soon.

via(ign)