There is no home screen: the page loads and the bit is already turning. Every metre it cuts pays ore, ore is the only thing you spend, and there is no timer, no lives and no way to lose — the well keeps producing while you read the panel, and it keeps paying while the tab is closed.

Twelve rig tracks are what you spend it on: a bigger bit for speed, coolant to cut the rock's hardness, a wider hopper for richness, a night shift that makes coming back tomorrow worth more. Ore is paid per metre rather than per second, so a hard layer is automatically both slower and poorer — and every one of the eight strata is harder and poorer than the one above it.

The well decelerates rather than merely slowing, and that wall is the whole point. When it stops being worth it, seal the well.

Depth, ore and every rig level go back to zero, and the deepest point you reached pays out in cores. Twelve permanent core nodes never reset: speed, hardness liners, an old-workings charter that fast-forwards the shallows you have already drilled, a foreman that buys levels for you while you are away.

The payout is superlinear, so one deep run always beats two shallow ones.