[JoachimS]

Yes, this is very cool! And impressive!

The only other compiler for 6502 I've ever used (and had to modify) is the old cc65. The original author stop developing it (10+ years ago): https://cc65.github.io/

But there is some development ongoing: https://cc65.github.io/

Would be interesting to see comparison with the new one.

[TedDallas]

I experimented with cc65 and wrote a simple game that ran on my actual C64 hardware. It was a lot of direct memory access, unrolling loops, and avoiding stack usage. A fun time overall, and it ultimately ran smoothly, but I see do why people who attempt anything serious on a C64 tend to focus on using ASM.