I was playing a quick game, clicked a mine and it was impossible for it to be a mine based on the numbers. I was about to screenshot and post it here when I realized that I had scrolled to perfectly hide the bottom row of the game, which changed everything.

There's another HN post right now about a UI problem costing Citibank $500M. It seems like this is somewhat related in my mind. If the application had made clear to me somehow that I wasn't seeing all of the information I needed to see, I wouldn't have failed. Not that it matters in this case. Just an example of how common these sorts of problems are, and how hard it would be to find and prevent all of them.