There's something fishy going on in the city of Waterdeep. The Lords of the city have traced the source of the problems to the underground catacombs and a party of four heroes is commissioned to investigate. Immediately, they are trapped with the ceiling collapsing at the entrance. So now, the four are on their own with no outside help or supplies available. The only direction to go in is down...
Eye of the Beholder is a roleplaying game in the style of Dungeon Master. Your party is moving in distinct steps and turns of 90°, weapons and items are controlled with simple mouse clicks. Fights are done in real time, with each character only being able to use his or her weapon once every few seconds.
Apart from the obvious AD&D based character generation and progression, there are only few classic roleplaying elements in the game. You can find new weapons, but there aren't any cities or merchants or most of the other NPCs you're likely to come across in an RPG.
Instead, the main point is finding one's way through the underground maze which includes avoiding traps and opening doors a lot. The corridors look pretty much alike everywhere, there are secret passages all over and there is no automapping - not an ideal combination. A printed map of the first three levels comes with the game, but since such a map doesn't indicate your party's current position, this isn't an appropriate replacement. Also, the numerous teleporters aren't marked on that map anyway. So there is really no alternative to picking up a pen and a piece of paper to map everything yourself.
On the other hand, Eye of the Beholder is a very accessible game due to its intuitive controls. The lack of depth, which might be criticized, means that casual players can easily get into it without need for lots of commitment. You can easily start playing the game, then let it be for a few days and immediately get into it again - and that's a quality which shouldn't be underestimated.