Solution for the ZX Spectrum text adventure "Dungeon" (1984), published by Cascade Games Ltd.
Note: This game is not on the well-known "Cassette 50" compilation, rather it is found on another Cascade release, "Cassette 4 - Vol 1".
In this game, you proceed from one location to the next in a way which is hard-coded into the program such that there's no general freedom of movement as found in most text adventures. i.e. once you proceed to the next room, it is impossible to go back to the previous room again.
It does feature some unique monster names though, like the GORPHIG.
Text walkthrough:-
HIT GUARD, TAKE KEY, UNLOCK DOOR, RIGHT, RIGHT, TAKE SWORD, USE SWORD, TAKE KEY, DOWN, 1, UNLOCK VAULT, LEFT (YOU ARE FREE!)