Shadow Tower [NTSC-U] ISO
[SLUS-00863]

A first-person RPG, dungeon crawler. Unlike traditional RPGs this game does not have XP. Instead your powers gets stronger with every monster you kill. This is a dark, ominous game with no music or automap.

A great game...wonderful for those who are looking for horror and puzzles.

Oppressive atmosphere and brutal difficulty.
The first of two hardcore first-person RPGs developed by the same team that brought us King's Field and Demon's/Dark Souls. As a King's Field spin-off the mechanics are extremely similar, and the controls are just as archaic.
Currency is somewhat limited, combat isn't too great, and you level up by using items called Soul Pods. Just like any FromSoft RPG, there's a steep learning curve and the main appeal is overcoming it through experimenting and exploration.
The sequel, Shadow Tower Abyss, is on the PS2 (Jap only, but has a full fan translation) with more mechanics, darker atmosphere, and tons of exploration. It's more survival horror, though.