3D shouldn't affect what it supports. 3D primarily adds a computational load on the device which significantly outweighs network load.

FPS generally requires a low latency, high reliability server. If the device is on wifi, it could work. On 3G/4G, FPS on mobile is tricky in general. Shooters can work fine, as long as there is a relatively lax error tolerance.

As of now, it can support MMOs to an extent. We haven't focused heavily on compression of network data, so network calls can get a bit bulky if tons of players need to constantly ping each other 10-20 times a second. This extra delay would cause characters to be more and more out of sync. If your game has a few characters (2-8ish), it will work fine.

We haven't implemented lockstep for hardcore RTSs. That said, if you periodically enforce state synchronization (ie: hash the game state to make sure that everyone is synced), you can do it with a few minimal blips. It's largely about how real-time you need it to be.

Supporting these are our long term goals. As of now, arcade, casino, puzzle, and action are all feasible.

Hey guys, I've been working on a real-time multiplayer framework that I thought some of you might find pretty useful.
www.soragora.com

The java client syncs up the server to handle all the network communication between multiple clients and ensures one is synced.

The authoritative server also handles player matchmaking and room hosting. If you don't want to host it yourself, you can always use the cloud service.

If you're interested, sign up and I'll send you access to our Java client and server. It's designed for Android, but it should also work on desktop games. Hope it helps!

Good read: http://www.gamasutra.com/view/feature/3094/1500_archers_on_a_288_network_.php

Not Java, but good resource:
http://docs.unity3d.com/Documentation/Manual/NetworkedMultiplayer.html