The presence of "enlace de descarga" (download link) suggests a specific demographic: Spanish-speaking Latin American gamers who rely on emulation due to the high cost of original hardware and software. In this context, "normal" becomes a relative term. For a gamer in Argentina or Mexico, it is normal to download ROMs from forums. It is normal to patch a ROM to add a shotgun. It is normal to ignore Nintendo’s cease-and-desist letters.
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With that in mind, here is a general guide on how to approach modified games like this: The presence of "enlace de descarga" (download link)