While primarily known for Nintendo DS emulation, melonDS also supports 3DS games. Its straightforward interface, BIOS/firmware support, and unique online/local multiplayer options make it an appealing alternative.

Physical 3DS cartridges and official eShop downloads are heavily encrypted by Nintendo's proprietary security keys. A standard, unmodified 3DS console can read these files natively. However, if you attempt to load an encrypted .3DS or .CIA file directly into a PC or Android emulator, the game will fail to launch. Decrypted ROMs

Once you have legally obtained ROMs (by dumping your own cartridges), you'll need an emulator to play them on your computer or mobile device.

In most jurisdictions, downloading copyrighted ROMs from the internet is illegal, even if you already own a physical copy of the game. Intellectual property laws generally protect copyright holders from unauthorized digital distribution.

This is the most important section of this guide. While emulation itself is legal, the source of your ROMs is what determines legality. Downloading a ROM of a game you do not own from a website is copyright infringement and is illegal in most countries. Game publishers, especially Nintendo, aggressively protect their intellectual property and have taken significant legal actions against ROM distribution sites.

Place your retail game card into the console.

The Ultimate Guide to 3DS ROMs: Preservation, Formats, and Emulation