It is called Miners Disturbance and the mining sytem is like that in Terraria but it is not very sandboxish
The only thing like miner disturbance is that you can see through walls and the water physics, nothing else. And no one remembers Dig Dug?
Sadly, I could never get past the forest area.. I die too much due to obsessively trying to gather every open-aired resource I can find.
Spelunky? Sure. Cortex Command? Uuuhh.. well, I don't see the similarities, and CC is so ridiculously flawed and boring...
The similarities in CC are pretty much the fog of war, splatter of defeated enemies, destructible environment, etc.
Completionist and symmetry-related OCD for me. All my constructions are symmetrical. At least horizontally or vertically, in some form.
So I can lower myself down a frickin ledge AND have a persistant path back up. I do agree that the grappling hook is vastly superior, though. Really!? I love that game. Maybe you aren't doing it right.