Perhaps I could be of assistance and maybe remake/port this to the enhanced version of Sinclair BASIC called Boriel Basic.
Other than that, this is a really solid concept and it is making me excited for my own journey into programming.
Hold on a sec.
Documentation on the compiler itself.
Book on Boriel Basic itself on Amazon.
ZX Basic Studio which uses Boriel Basic, also recommended by the Boriel Basic book.
Here are some links to get started. My only tip is that if you're used to Sinclair BASIC, there is a mode in the compiler and ZX Basic Studio that helps with compatibility among other things. Good luck and have fun.
PS: I should note that Boriel Basic is mainly just a compiler with extra bells and whistles and you can use it in any text editor such as VS Code and Geany.
PPS: Here's a link to Boriel Basic in the VS Code Marketplace.
No problem. Sorry for the extra long post. I just wanted to give you as much resources as possible in case if you wanna remake this game to be even less sluggish. Other than that, it's still a very great concept.
If you want to open-source this and/or another one of your games, may I suggest getting yourself a github or gitlab repo? It would help for backup reasons mostly.