Solid open source are :
Ogre3d
Irrlicht
Axiom(based on Ogre 3d)

And lot of others that were open source from the beginning.

Torque 3D has failed, too much problems, and severe old bugs etc ... and open source don't have changed anything.
I would like to see it really rising , really ...
But it's not totally open source, and there is the same team behind expecting on selling models and stuff for business, so there is a MONEY GOAL.

Ogre 3D and Irrlicht are real open source projects, no money goal behind at all. And some fans like that a lot and stick with them.

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NeoAxis, is lacking documentation , is not bad at all.
I would alos like it to really rises ...
But i think it dont' have convinced people enought, the best thing for it should be to find some programmer fans , really making it evolve and bringing docs.

It's like mmo that fails, they just passing the free to play model; but it don't guarantee that the mmo will encounter some better success when it has failed on the month pay model.

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Perhaps the developper don't sell it enought and he is tired of development and feels he must do something else.
He has never done good docs, so he is not totally enought implicated on the users asks, he just made it , and say, it's good and easy, just pay and use it and for docs try to find by yourself.
For me it's not so quality to don't have enought beginners and newcomers good tutorials and docs.

It has big potential, with very complete level editor, pathfinding system ,solid physic and particles, shaders etc ...
Well ... juts good luck