Morrowind has been out for several years now and has been surpassed by the fourth installment in the Elder Scrolls series, Oblivion, but TES3 Morrowind still stands as a monumental achievement.
Basically, a sandbox game set in a high fantasy environment Morrowind gives the player complete freedom to pursue any path or follow the complex story line. Along the way you can rise to prominence in several of the gameworld's institutions and follow any or all of the game's hundreds of sidequests to achieve fame and fortune.
As with most rpg's you roll a character with stats and skills and then use those skills in the gameworld to level up. Vvardenfell is vast with varied environments, weather effects, day/night cycles and aggressive inhabitants. Combat is engaging, whether magical or melee, and alchemy and enchanting are available to buff your character or weapons. Two expansion packs, Tribunal and Bloodmoon, make this huge game even grander.
This game has been on my hard drive for more than three years now and never seems to get old. The modding community has created so many variations and tweaks that anyone can have an almost unique version to suit their preferences.Highly recommended.