Nintendo-64

Buried deep inside the game’s code, there’s a fully functional emulator with 10 playable games for the ZX Spectrum system (UK’s version of the Commodore 64). Now you can play games like Lunar Jetman, Gunfright, and Knight Lore inside of GoldenEye 007.

The company that developed the game, Rare, was tinkering around with system emulation for the N64, which was a new console at the time. Instead of removing the emulation, Rare just disabled it with a patch. However, spoondiddly discovered how to re-patch it.