A period, multiplatform alternative: Usborne's Write Your Own Fantasy Games by Les Howarth and Cheryl Evans from 1984 https://drive.google.com/file/d/0Bxv0SsvibDMTel93SThEYkJkZHc . (Generously provided by Usborne https://usborne.com/gb/books/computer-and-coding-books )

Cool! Though your Google Drive link asks for permissions, you can use this instead: https://usborne.com/row/books/computer-and-coding-books

The review of the book isn't so good, though I'd still own it as a charming period artifact: https://gmkeros.wordpress.com/2024/01/19/write-your-own-fantasy-games-for-your-microcomputer

Dungeon Crawlers for the C64 always make me think of the Sword of Fargoal! https://www.lemon64.com/game/sword-of-fargoal

For those as confused as I was, the BASIC as written will not run on a C64 (two immediate notes: BASIC 2.0 doesn't have labels, and a variable like STATS would be illegal because it clashes with the status word ST). This only works in their custom IDE which "compiles" (read "adds line numbers, alters names and tokenizes") it.

Yeah seeing GOSUB and no line numbers was an instant warning light.

To be fair, this isn't that different from things we'd do back in the day.

I use to write BBS software in BASIC on the C64, and one of the things we'd do is use a "compiler" that would do some optimizations. What this allowed was being able to write a program too big to actually run, but the optimized version of it could.

I wish I could share more details and be less hand-wavy... but it turns out the 80's were a long time ago and I just haven't given it much thought since then (at least until I saw your comment).

RGC Basic: https://retrogamecoders.com/rgc-basic/

"Commodore BASIC–style interpreter written in C, but with modern conveniences."