I really hope Patrick won't mind me saying this, but... that initial downloadable Java version really was quite bad. You could resize the Bingo window smaller than it should be, causing all kinds of bugs that made the bingo cards completely unusable. Only quitting the program & restarting would fix it, resizing wouldn't. I remember this because I kept looking at his program at the time, wondering why it was successful, how those bugs slipped through whatever beta testing he did. I assume the marketing (especially SEO) is what filled that gap, as well as understanding what his customer demographic would tolerate.

Of course, the product improved greatly over time as well, so I really don't mean this as a criticism. If you want an example of a true minimum-viable-product, Bingo Card Creator 1.0 had to be it.