Tower of the Sorcerer is an old (first released in 1998) game created by two indie developers in Japan, Oz and Kenichi. Although its site is still up (linked to above, charming 90s design and all, complete with an auto-playing midi), the download link doesn’t seem to work on it, but the one here does.
It may look like an RPG, but it’s actually more of a puzzle game. The video Let’s Play by Malefact will give you a feel for how it works. The game bears some resemblance to another game series, Deadly Rooms of Death, in particular DROD RPG (which Tower of the Sorcerer served as inspiration for), but is otherwise unique in its play experience.
It’s very addictive, it had me playing it most of today, and it’s extremely difficult — do save often because it’s very easy to get yourself into a situation where you can’t advance. The video Let’s Play does go through the entire game for those who may have trouble solving the game.
TIGdb: Entry for Tower of the Sorcerer