I enjoyed playing this game. It simple and fun to play. I really liked the idea and visuals, but it not fits the theme at all(I know that you ran out of time, but feedback is feedback).
I think it would be better to add instead of timer some negative feedback for player checking every square and add something to let know player besides sniffing. And with that it would be more of puzzle game where player checks everything before digging. But that just how I would do it if I had time.
Overall, nice little game. For me, it's solid 4/5 because it doesn't fit the theme and it could be better in some places such as tutorial being on the game page and adding some juice to player's action.