Libre MMO games

Hello!

So I'm moving to libre system and I am wondering if there are any nice libre MMO games?

I have been playing a game called Transformice for a long time now. I don't even go there for playing games, because you can just use the game to hang with friends and build maps or play various minigames. Unfortunately, it requires Flash and won't work with Gnash, Lightspark or Shumway.

Therefore, does anyone know of any good libre MMO games? Preferably not an RPG, or at least not a grinding RPG. Non-massively multiplayer suggestions also welcome. I just want it to be playable even without the use of port forwarding.

During my searching, I found this nice database: https://libregamewiki.org/Main_Page Unfortunately the multiplayer games in there did not interest me very much. So it would be great if anyone knows about a good game that is libre or at least doesn't require proprietary software to play. Help much appreciated, thanks!