Hi there. Thanks for your interest in Bruce Lee - Return of Fury
I wrote a little "post-partum" about it on my site: https://rebelandroid.com/games/bruce-rof
Anyway. The first thing to do is to make the code relocatable - all the tables (map data, map properties, text lookup table, colours, map init, exec routines) and self-modifying code + irqs
must be "labeled" properly so that you can move stuff around at will without side-effects. That's a given.
The graphics are mostly the same as the C64 version - but the C64 screens are stored as 40x11 rows, where every odd line is the even char | 0x80 - I didn't quite see that on the
atari version, but I may be mistaken.
Ron J. Fortier said to Retro Gamer Magazine (issue 145) that the C64 version was sort of an atari "emulation". That's why I think you should base your code on the original, not
the "inferior" port - and, true enough, the Atari version plays much smoother. I think this is due to the "emulated" port - instead of using multicolour sprites, he opted for
TWO double sized single colour sprites for each character, except the Ninja. Additionally, an extra sprite is used whenever Bruce kicks or gets "hurt bad".
Edit: AND that's not all, he ran out of sprite pointers/memory, so the sprite frames are doublebuffered and copied in using CPU on every frame. Phew.
Needless to say, this can be quite inefficient, and so the C64 can't really keep it at 50 (60) hz, so he's forced to skip a frame or two to get enough time.
However, it's still the version I grew up with and love, so I lean towards it - no offense.
I'll be happy to be of assistance should you need it.