FUNCTIONALITY COMPATIBILITY No system modifications of any kind required. Plug Play! Works perfectly in any original Nintendo system, the original toaster NES or top loader, Retron HD, Retron systems 1, 2, 3, Retro Trio, Retro Bit, and all other good quality HARDWARE clone systems such as the Gamerz Tek systems. THIS CART WILL NOT WORK IN THE RETRON 5 AND RETRO FREAK SYSTEMS - these are Android emulator-based systems, not hardware-based. Will work with the Game Genie per all reports and testing. All codes *should* work, but cannot be guaranteed. NTSC (US) and PAL (EU) System Region Compatible. To switch regions, rapidly press the reset button 4 to 8 times very rapidly with the game in and the power on so that the system light is flashing. The system light will stay solid when set to the proper region.