Really!? Wow. I don't see how, will read about it. Do you have any link to read? (any excuse to read about Sid Meier's Pirates! and the C64 is good).
In any case, C64's BASIC "programming" meant that for graphics and audio you were mostly POKEing and PEEKing, since its instruction set was very limited. And when you're mostly peeking and pooking directly at memory, you're barely writing BASIC, are you? ;)
edit: I tracked down a 2014 comment from HN saying the same as you: that Pirates! was mostly written in BASIC. I'm amazed. Now I really want to see the source code and/or read a "making of".
I don't remember if it was compiled BASIC or if you could actually freeze the game and print the listing. I do remember that it was mostly BASIC as I mentioned though, meaning that it resorted to ML routines when needed.
It is debatable if using PEEKs and POKEs for audio and video functions changes the fact that it is actually BASIC. You are only imitating LDA and STA opcodes, the rest is still BASIC.
Awesome. Thanks for the info! I'm really surprised by this. I didn't know you could do anything useful with C64's BASIC. I know I didn't. I waited till I had GW-BASIC on a PC XT to really learn how to program.
If Pirates! was mostly high level BASIC, I wish the source code was available somewhere to read. Kind of like Broderbund, which released the assembly language code for some of its old games...
It should be pretty straightforward to extract it from the image file using the modern emulator/debuggers. I believe the comments (if any) will be scarce, but still...
