The GOG release of this classic doesn't really do it justice in my opinion. The original version (I guess a close resemblance of the 1980 release) lacks sound, the impressive title screen and a functional questing system. The quest system not functioning correctly makes the game incompletable and needs fixing ASAP. There is however a 1998 version that comes with the purchase. Yes, the horrible quest bug is fixed and sound effects, even music is present. Still no impressive title card. But what is missing is the randomly generated overworld and dungeons, this takes away a very key aspect of the game. You can choose a seed for the overworld and dungeons with the lucky number, but some of the seeds are very awkward, forcing the use of a magic amulet to get to lower floors. Although the save feature is a god save (it's Q by the way, it's not speciified in the Introduction). Overall the game is playable, but has just been messily ported with both versions containing bugs that either break the game outright or sacrifice an integral part of the game. Since it is quite fun and proves to be a good time waster and considering it's a 1980 game, it's truly revolutionary, just needs the bugs fixing and it could be great.
