Abyss Sweeper

Abyss Sweeper takes the minesweeper grid and drops a drilling rig into it. The numbers mean what they always meant — how many mines touch this cell — but you cannot simply avoid the mines, because your fuel drains the whole time and harvesting a mine you have correctly located is the only way to get it back. So the deduction stops being about staying safe and becomes about finding the mine fast enough to live off it. The shaft never ends; how deep you get is the score.