鍵とアクセスカード

ROI is lifetime yield divided by purchase price — the average value looted per successful run, multiplied by the key's durability, against what it costs to buy.

Three things it does not account for, and which will move your real numbers: the loadout you lose when a run goes wrong, the time cost of reaching the room, and the fact that a contested room is often already looted. Every yield figure is community-reported rather than measured by us.