Version 4.9:

https://rcbasic.freeforums.net/thread/957/rcbasic-v4-9-out?page=1&scrollTo=9382

The author of the language is really diligent. 

Ha...I want to know whether there will be a big change in version 5.0.

By the way, I discovered a discussion about RCBasic in the following forum! 
https://www.syntaxboom.net/forum/other-languages/1776-rcbasic

Also this one:

https://www.syntaxboom.net/forum/app-game-kit/1810-is-agk-studio-basic-interpret...

https://rcbasic.freeforums.net/thread/959/v4-10-plans?page=1&scrollTo=9386

The to-do list of version 4.10. 

Version 4.10 was released: https://rcbasic.freeforums.net/thread/985/rcbasic-v4-10-out

Actually, a detailed beginner's guide for getting started with Nirvana2D was released recently:
https://rcbasic.freeforums.net/thread/984/nirvana2d-beginners-guide?page=1&scrollTo=9545