Ex-Sachen developers refers to an unknown development team, believed to mostly consist of ex-Sachen staff, who worked on a number of pirate platform games and other unlicensed games for the Famicom in the mid to late 90s. Several such games were programmed by Ei-How Yang (also known as E.H.Y. and variations such as Yi-How Yang), who mostly worked on Game Boy titles for Sachen. He is often the only person credited (although the credit is usually hidden), but he presumably worked as part of a larger development team.