Speaking of keys, I vaguely remember there being a key which, when held down and a direction key pressed along with it, would make the digger dig on the square adjacent in that direction. If the target tile was soil or diamonds, it would disappear, while the action would not have any effect on the other types of tiles. I tried the usual SPC/CTRL/ALT, but they don't seem to work in this way. Am I misremembering this feature, or is it simply not part of this implementation?

if you just play around a little bit it's not that hard to figure out

> the game is particularly uninviting

This is what made games so much more interesting back in the day.

Games that tell you what to do the entire time aren't more "inviting." They just want your time so you'll buy horse armor when they offer it.

You just described a majority of games from this era.