Keeping it on the Metastasis map page is actually much more on-topic, since the map is essentially complete. The future of it should be discussed more openly, especially so that I don't have to answer the same questions more than once.
Same reason I'm answering you here, instead of on yours. This isn't a private discussion, it's a very public one, so let's make it as easy as we can for everyone to see it.
as for your actual question here: It will most likely be 3D, although given that the gameplay takes place in 2D we may switch over to high quality sprite action instead if we don't get a good art team up. Not sure there, it's not a priority at the moment. And yes, multiplayer would be a part of the engine, obviously (Metastasis is pointless in single player, after all), and would be vastly customized specifically for Meta, and integrated with our website for much improved statistic tracking over the old SirBot system.
We're building our own, actually, using Python.
Though we could move the discussion to our profiles to avoid general off-topic.
Wait, your own engine? And it will like be 3D and, you know, you'll be abke to play multiplayer or whatever with it, similary to League of Legends? Whoah...
P.S. I see you prefer to answer to people in your profile, but you should actually answer to them in their profile, else they don't get a notification.