Baldur's Gate: Dark Alliance is a one-player dungeon crawl game that is basically the official Dungeons and Dragons version of something like the classic Gauntlet. You choose from three character types, and go through a story-driven linear path, beating up foes straight out of the Monster Manual and building up your character all the while.
The reason the game is rated so highly by so many of us is that it does so many things right. It has gorgeous graphics, addictive (if slightly repetitive) gameplay, good level design, great voice-overs, a fairly interesting plot, excellent and intuitive control, and high replay value. The game isn't, and never tries to be, an RPG, so those looking for fascinating plot and branching storylines shouldn't look here. But for those seeking a good action game with a dosage of official Dungeons and Dragons rules & creatures, this is most definitely an excellent choice. It not only is fun the first time you play through it, but it beckons you back with its interesting levels and nuances between characters.