Related? https://www.t3x.org/files/floodfill.pdf
Basic interpreter for the code:
https://www.t3x.org/nmhbasic/index.html
To compile it:
unzip nmhbas3_32.zip
cc -O2 -DEXTRA -o tcvm tcvm.c
./tcvm basic
To run some basic programs: ./tcvm basic maze.bas
#3 = maze.bas
load #3
OK
run
Exit to your OS: system
OK, let's run the floodfill example from the PDF: ./tcvm basic flood.bas
#3 = flood.bas
load #3
ok
run
For a puzzle of this sort I would expect to be able to create multiple path segments and connect them later. I would be able to do this with paper and pencil. For instance on the first puzzle you can deduce the way 2 and 3 must be connected without knowing how to connect 1 and 2.