You have the exact assembly algorithm in the page. What you see it's what you get. Now, for real, I'd suggest getting lvltl (VTL-02) interpreter
written in C for a "bigger" language running not just under a VM, but for small machines and simulators such as the 6502 based Kim-1 and Apple1. With that "not enough to be called Basic" a Sokoban might be written with a bit of patience.
https://github.com/howerj/subleq/
As a goodie you can run Eforth on top which almost writtes itself. Compiler, interpreter, editor, IDE and a Sokoban, all in a simple VM.
Let's scale. Mu808/n808. Interpreters in C and AWK, a compiler in Python.
https://codeberg.org/luxferre/n808
You have the exact assembly algorithm in the page. What you see it's what you get. Now, for real, I'd suggest getting lvltl (VTL-02) interpreter written in C for a "bigger" language running not just under a VM, but for small machines and simulators such as the 6502 based Kim-1 and Apple1. With that "not enough to be called Basic" a Sokoban might be written with a bit of patience.