Just because Nintendo stopped selling the games does not mean the copyright expired. 3DS games remain fully copyrighted. Downloading them is piracy.
These files are raw dumps of physical 3DS game cartridges. They are primarily used with emulators like or specific flashcards (like the Gateway 3DS). .CIA (CTR Importable Archive):
Easy to use with emulators; no installation process required on PC.
Downloading copyrighted ROMs or CIA files for games you do not own is illegal. This information is for educational purposes regarding file management and homebrew software. using FBI or how to set up custom firmware