The game was pulled from the store after rights to the Spelunker series transferred from Irem to Tozai Games in late 2011.
Already known for having one of the "weakest" protagonists in gaming—where even a small fall results in death—the added darkness made this version famously punishing. Current Status: Lost Media
Because it never received a physical release and was exclusive to the Japanese PlayStation Store, it is effectively unavailable to anyone who did not purchase and download it before its removal.
Players can fire flares to temporarily illuminate a larger area, though this is often impossible in tight corridors with low ceilings.