Game Boy software, 12-piece set. All cartridges with built-in batteries have had their batteries replaced with new ones. Cleaned with anhydrous ethanol. ◾️Momotaro Dentetsu 2 ◾️Hiryu no Ken Gaiden ◾️Medarot ◾️Mazekko Monster ◾️Yu-Gi-Oh! Duel Monsters ◾️Kingyo Chuuihou! (Goldfish Warning!) ◾️66 Piki no Wani Daikoushin (missing part on the cartridge) ◾️SD Sengokuden Kunitori Monogatari ◾️SD Sengokuden 2 Tenka Touitsu Hen ◾️Super Mario Land ◾️Baseball ◾️Card Game I have confirmed that all of them work on my Game Boy. However, please understand that they may not necessarily work in your environment due to compatibility issues with the console. Please purchase only if you understand that these are used, retro, and junk items. No claims and no returns accepted.