Engine for 3d chat

It was an interesting topic on this forum some years ago:
http://www.devmaster.net/forums/arch...hp/t-5172.html

I'm wondering if the things were changed. There some 3D chats are exist and a lot of different engines has been developed as well.

However, the question is still actual for many people. What's the best engine to start developing new 3D chat.

I think that right now Unity3d is quite good engine to be used for regular 3D chat environment.

Could somebody advice me some other engine?

Do you know some problems with Unity which will make it the bad choice for this kind of application?

Thank you all very much in advance.

I wouldn't call it "3D Chat". They are called "virtual worlds".

Unity's networking may not be up to snuff for the first M in MMO. At least, that was the case up until months ago. Check their forums; lots of people were trying to figure out to scale Unity beyond tens of players.

Fundamentally, there is still no indie/affordable/free engine that scale really well at the "massive" part; they all have issues. However, the front runners are still the same ones as in the original thread. Basically, you want a hosted environment like Multiverse. Or rolling your own layer over libraries, such as OGRE + various libraries.

But, maybe Unreal's semi-freebie may be the way to go now? It's been put to MMO use many times before, but I don't know how much of its is customization and how much is built into UT3.