Bethesda came close to the perfect RPG when they released The Elder Scrolls IV: Oblivion. With Shivering Isles they may have achieved the perfect expansion.
Expansions for popular PC (and now, with downloads available on next generation systems, console) games are certainly nothing new, but rarely are they anywhere near as exciting as the original release. In most cases they simply add additional content or a few new missions; allowing for a certain degree of replayability or the opportunity to simply make the core game last a bit longer. The Elder Scrolls IV: Shivering Isles, the first full blown expansion to Bethesda's impressive Oblivion, does something more. This expansion does more than simply add to the experience provided by the core game; it improves upon it considerably.

Much of this improvement is seen in the main quest. The main aspect of this newly expanded story centers on a character named Sheogorath (that's almost as silly a name as the one claimed by the late Douglas Adams' memorable Slartibartfast) who will instantly have you thinking of a drunken version of Sean Connery - perhaps too many extra dry vodka martinis (shaken, not stirred) were imbibed by this guy. In any case, the dialogue delivered by Sheogorath had me in stitches more than once and probably will do the same for you.

Of course this is not just an adventure in comedy and the new quests and dungeons that Shivering Isles will throw at you will be more than enough to keep you adventuring for a good long time. The titular Isles represent a completely new island in the game, so there is a stark contrast between the new content and the more familiar world of the original game. Divided into the lush and alive area known as Mania and the dark and dreary Dementia, the quests offered here will vary from straight up dungeon crawls to exciting escapes and the ability to take on twisted roles such as mad scientist, grand inquisitor, and drug-addled junkie. You'll also have the chance to wield an impressive new sword (lots of 'em actually, but this particular one will be most people's fave) known as Duskfang and Dawnfang (its properties alter depending on whether it is day or night).