Short answers, pulled from the story.
Emulators developed through clean room design are legal in the United States. Court rulings including Sega v. Accolade (1992), Sony Computer Entertainment v. Connectix Corporation (2000), and Sony Computer Entertainment America v. Bleem (2000) all affirmed this. The Librarian of Congress codified these rulings as allowed exemptions under the Digital Millennium Copyright Act.
Freely downloading or uploading game ROMs from the internet is considered online piracy and may result in legal action for copyright infringement. Under US law, a user may dump a copy of a ROM from a game they legally purchased, but redistributing that copy is illegal under both domestic copyright law and the international Berne Convention.
The first recognized console emulator was released around 1996 and was a prototype project that eventually merged into the SNES9X product. Other early emulators of that era included Marat Fayzullin's iNES, VirtualGameBoy, Pasofami, Super Pasofami, and VSMC.
Apple began allowing emulators on the App Store on the 17th of April 2024, lifting a ban that had lasted nearly 16 years. Following the decision, emulators including Delta, Sutaato, and RetroArch appeared on the platform.
Nintendo sued the team behind Yuzu because the group had published information explaining how users could obtain decryption keys required to run Switch games, which violated the DMCA's prohibition on distributing tools to bypass copy protection. The team settled with Nintendo and removed Yuzu from distribution. Forked projects appeared afterward that informed users what decryption items were needed without explaining how to acquire them.
A hidden NES emulator running the game Golf was embedded in Nintendo Switch firmware until the 4.0.0 update. It was accessible only on the 11th of July, the date former Nintendo president Satoru Iwata died in 2015. Iwata had programmed Golf himself, and its inclusion was described as a digital form of omamori, a traditional Japanese amulet intended to provide luck or protection.