i want to develop a 3D game client framework. but i am also interest in unity, orge3D. and even torque3D.
unity has fbx already in and you can program in c#. there are some things missing in the free edition, such as navmesh and c++ addons.
you can get more information at
http://unity3d.com/
ogre is already open source and written in c++ but it doesnt support fbx. you would have to write that yourself. there is at autodesk fbx sdk. there is also a c# wrapper at nexoaxis (or something like that).
http://ogre3d.org/
Torque3D is interesting. i did some compile and little work with that long ago. but now 1.2 is open source.
http://www.garagegames.com/community/blogs/view/22106
http://www.garagegames.com/
other clients are too specific for their own games or too social (like second life client).
for modern games you need:
- collada or fbx (or both)
- physics
- navmeshes
- textures, materials, shading, etc
- a game (EQEmu is a good source)
for me, is a little hard because i want to keep the streaming in but rip out a lot of stuff that doesnt contribute to the framework. i also want a c# with c++.
finally, have 32 people limit with something like hygrid taking you from place to place. since that is still being worked on, i will have to wait. my problem with sl client is a bit different, but with a good game engine, EQEmu could be possible. i just dont know what EQ live doesnt for its huge objects like freeport.