(Or, if the game includes any attractive women or men.) Some games are deliberately designed to be easy to modify, including a 'construction set' of sorts to build levels, weapons, etc., and whole modding communities spring up as a result. They can be unofficial (new maps or new equipment in the same game), completely unrelated games that merely use the source game's software as a backbone ('total conversions'), or just quality-of-life adjustments to the original, such as, bug fixes, character appearances (which can often lead to scenarios). Game modifications, or 'mods' for short, are any alterations to a game that were not made by the game's license holder. Just because the game designers made a good game doesn't mean you can't make it even better.

Megaman 9: Rom extraction.BRSAR files.BRFNA files. But the Mega Man 9 download could have easily.

I do think that there will be a MM9 NES ROM hack though. 6 min - Uploaded by ValientlinkI was browsing around on the internet one fine evening, and I stumbled across this.

Mega man 9 nes rom hack