Cadaver

"Cadaver is an isometric action-adventure game by the Bitmap Brothers, originally released by Image Works in 1990, for Atari ST, Amiga, MS-DOS and Acorn Archimedes. In the game the player controls Karadoc the dwarf. (...)

In the original Cadaver, Karadoc, who is a gold-hungry dwarf and really just hopes to find a treasure, is on a mission to seek out and kill the necromancer Dianos, the sole remaining inhabitant of Castle Wulf.

The game consists of five levels representing different floors of Castle Wulf. Entering the castle via the sewers, Karadoc works his way up from the dungeons, through guard chambers, royal hall, the king's private chambers and finally the battlements with Dianos's sanctum."

Source: Wikipedia, "Cadaver_(video_game)," available under the CC-BY-SA License.