Other rendering engine except minecraft client ?

[Tarmik]

You can login with any client that uses the Minecraft protocol from either 1.7 or 1.8. You can find some clients here, but not all of them render stuff. Most of them are console-based.

Thanks for useful link.

I've scanned most of minecraft clients, and I think I have some ideas of not making my own 3d rendering client engine, but may be some sort of bot. (chat / navigation)

What I have checked through - there aren't any good C# / C++ bot solution, most of up-to-date solutions made with javascript / pyhton, but could not make some of them work.

May be I'll still fall down for my own C++ / C# implementation - it will be either custom implementation or somehow chopped off from mcserver / cuberite.
If you see it useful - I'm eager to discuss with some of your developers how easy / feasible it would be to make something like this.

minetest is not interesting for me anymore due to it's licensing restrictions:
https://forum.minetest.net/viewtopic.php?f=7&t=11261

Good that cuberite does not have same problem.