A feature I like in that game is it will grey out numbers once you’ve sufficiently annotated the adjacent spaces.

It’s a really good game, but you need to pay $5 to get rid of ads.

I got stuck and couldn’t figure out what to do next. Maybe as a first clue, you can highlight the next cell they should be able to figure something out about (either clear it or flag it). If they’re still stuck, then you can clear it or flag it.

Even better would be to explain the logic for why it’s safe to clear that cell or why it should be flagged, but I know that’s harder to implement.