If you ever come back to this game, I discovered that after I pick up gold, I get more gold each time I dig straight down. That stops when I move to either side. The best way to get a high score is to look for gold with long columns of dirt under it (and no greenies nearby) and dig down to the next screen.
There's just enough here to make for an interesting game. I don't know that being able to move sideways to new screens is necessary. limiting new screens to straight down would remove the need for the ("Y/N)?" prompt, making the game flow faster.