I've been really enjoying this game! Thanks so much for putting effort into a game on a niche console like the Playdate :-)
I have a few suggestions after a few hours of playtime:
1. I'd love to see more difficulty options or some kind of additional progression since, after getting good enough to beat hard mode most of the time, it doesn't feel like there's as much point to continue playing.
2. Change the ability to mark a tile as a "0" to the ability to mark a tile as a "?", indicating that you know a tile contains a 1 or a 2 but don't know which number it contains specifically. To me, if you know a tile is a 0, it makes sense to just collect it immediately, so I never mark tiles as 0s. However, there are many times when I know that a tile is greater than 0 but can't tell whether its a 1 or a 2 and it would be helpful to be able to write this down.
3. The music is pretty simplistic and short. It'd be nice if there was some more varied and longer music. A few different tracks would be great.
Again, awesome job on this game! Thanks for sharing!