The Cat's Meow home ROM (new rules for BAD CATS pinball). Playing a game with difficult rules. 

Great timing! Release of version JP-1.0 is planned for this Sunday, December 10, 2023. For updates and documentation, see pinside.com/pinball/forum/topic/the-cat-s-meow-a-new-home-rom-for-bad-cats

could you make a tutorial how you do this?

All old pinball code is written in assembler, so you need to be familiar with Motorola 6800 assembler. The steps involved are 1) disassemble the binary code to create assembly source. 2) Reverse-engineer the code to determine what each routine does and also the meaning of all variables and flags. 3) Figure out how to modify the rules to make the game more fun. 4) Modify the code to implement your changes. #3 is the most difficult. #2 is technically challenging. The rest is easy. I made the patch with the 7eleven pinball disassembler/compiler, which is freely available on github but almost completely undocumented. There is a thread on Pinside that explains how to use 7eleven with Williams games that are about 10 years older than Bad Cats and therefore a lot simpler (pinside.com/pinball/forum/topic/7eleven-tools-for-disassembling-and-compiling-system-6-11-games). There is another thread on Pinside about this patch, with lots of technical information (pinside.com/pinball/forum/topic/the-cat-s-meow-a-new-home-rom-for-bad-cats).

If you send me an email to username-at-mailbox-dot-org I will send you the patch files.

@@idealjoker I don't get it. What shall I send an email to?