DOS PCs were the lead release for Willy. There are two versions as well, the floppy original which supports the soundtrack on MT-32, and a CD "multimedia PC" release which is basically the Sega CD version in 256 colors(no MT-32 sound, just SB/Adlib).

The game has some clockspeed bugs on DOS, though. The animations play at the correct rate, but timers that use the in-game clock will fire too fast above about a 66mHz 486 speed. This left me stuck on a puzzle for a few years, since I first got to play the game in the late 90's and it wasn't obvious that I had a bug.