Is there any way I can pay for the source code so I can see how you did a lot of this stuff? I know there is a video but I'm really interested in what you did and want to see how they were done in assembly. Also did you write the Windows version in assembly too or C?
Probably some kind of wrapper / emulator for the NES rom?
I assume the Windows version is just bundling the ROM with a NES emulator.
Even without the source code, you can use a NES debugger/visualizer tool such as Mesen to see what’s going on in the CPU and PPU. Great for ROM hacking too. Read the Mesen docs for more info.