A technical question for you around the porting being a dead end:

I see from other replies that you now understand the code reasonably well and feel you can expand/extend it while keeping it in BASIC. However, I note you've also done project where you automatically ported Fortran to Lua - are you not interested in trying to do something similar for performance/maintainability reasons? Is there an advantage in keeping it in PowerBASIC?

I've wish listed the game, and look forward to playing it, it sounds like great fun - even the manual sounds like a good read.