8-in-1 Gameboy Color cartridge produced by a Taiwanese (?) company called Sachen, which is infamous for making unlicensed games for various consoles.

Sachen have brought out a fair few games for NES and Gameboy, and at one point even made efforts towards their own handheld system - Mega Duck, I believe. Go ask the internet. In this case, they've released a few 8-in-1 carts for the Game Boy Colour, and I have one of them.