The Game Boy may not had been the first handheld with changeable cartridge games that honor goes to the 1979 Milton Bradley Microvision (More on that on a later date) but Nintendo has some heavy hitting IPs on there belt and made the Game Boy a house whole legend.

The Game Boy was Nintendo's second handheld system following the Game & Watch series introduced in 1980, and it combined features from both the Nintendo Entertainment System and Game and Watch. It was also the first handheld game to use video game cartridges since Milton Bradley's Microvision handheld console. It was originally bundled with the puzzle game Tetris.

In the summer of 89 I got the Game Boy and the first 5 launch games from K.B. Toy Store and they are,

Alleyway

Baseball

Super Mario Land

Tennis

Tetris (included with handheld)

https://www.furaffinity.net/gallery.....es-Video-Games