One day, Alex received a cease-and-desist letter from his ISP—a forwarded notice from Nintendo. He hadn’t uploaded anything, but a tracker in a popular ROM had logged his IP address. Frightened, he deleted his ROM collection and uninstalled the emulator.

Emulators like Yuzu (discontinued after a lawsuit) and Ryujinx (also later shut down) mimic the Switch’s hardware on a PC. They translate ARM instructions (the Switch’s processor language) into x86 code (what PCs understand). ROMs are simply cartridge or eShop data ripped into a playable file.

Alex falls into the latter. “I own 30 Switch games,” he says, showing a shelf of cartridges. “But traveling with them is a pain. Having ROMs on my laptop lets me play anywhere. Plus, I can back up my saves.”