When Retro City Rampage comes to WiiWare tomorrow it'll include an 8-bit version of the game called ROM City Rampage. Provinciano was developing what's now become ROM City Rampage almost a decade ago for the NES, but abandoned it to focus on Retro City Rampage because of the hardware limitations - a wise choice. After releasing the open-world crime game last year, he decided to come back to his 8-bit aspirations and crunch the modern Retro City Rampage into a truly retro game.
In this video, Provinciano explains the difficulties he had in creating ROM City Rampage. Even if you're not hugely interested in how games are or were developed it's a good watch, and not too inside baseball; Provinciano neatly explains some of the data-saving processes he had to employ, such as sprite mirroring and combining duplicate tiles of pixels.
ROM City Rampage will be included as a playable prototype in the WiiWare release, and come as a free update tomorrow to the PC version, which you can pick on Steam at half-off for one more day.