SheepShaver is not perfect (it cannot run MacOS 9.1 or 9.2), but enables users to run the vast majority of PPC software for Macintosh on their PC, which is all things considered, extraordinary, especially back in the year 1998.
SheepShaver started as a commercial project in 1998 but is now open source since 2002. SheepShaver is a PowerPC (PPC) emulator which allows you to run Mac OS 7.5 up to Mac OS 9.0.4 on various platforms, such as on Windows. What is SheepShaver PPC emulator (for Windows + Mac OS X)?