going to try the android version it says also linux
Viewing post in RCBasic - BASIC Programming Language for Games comments
RCBasic should build on ARM but I don't have a Pi to test it on at the moment. If you want, you can grab the source code and try building it yourself. I don't have an easy build process on linux setup so you will need a good understanding of C++ toolchains to be able to build it.
I made a video on how to build RCBasic on Windows. The script I used in the video would have to be converted to a shell script but everything else should be mostly the same on linux: Building RCBasic From Source