Aah, that'd explain it. I'm not sure why I assumed that Windows Minesweeper wouldn't have needed much further development after it was written; after all, I can never leave things alone once I've written them so I've no idea why I assumed Microsoft could :-)
I distinctly remember getting boomed on the first click several times on one of my father's computers. I can't quite remember if it was 95 or 98 that one had, but it was ninety-something.