tonyrocks wrote:So, how does one start with porting a c64 game to the vic-20?
The most important step is to choose a game which can be ported with acceptable effort and reasonable likeness to the original. I guess one could do a recreation based on observation of the game in action, but for a more faithful port the original needs to be disassembled.
- Choose suitable game
- Find (or create) a comfortable disassembler
- Disassemble until the I/O is understood and code/data can be relocated
- Replace graphics with placeholders
- Replace I/O with VIC code
After that it gets messy.
Crossroads was a reasonably easy game to port as it does not rely on sprites and the level design is not that crucial and can be squished to a half-width screen. The sound is simple too. The one unexpected complication was the use of color to determine the creature alliances which needed some extra code/data to work on the reduced set of non-multicolor colors.
Anyway, I hope you enjoy the game!