Shivering Isles will probably be a little hard to adjust to, either for old-time Elder Scrolls fans or for people jumping in at Oblivion. Shivering Isles’ main storyline is actually more interesting, more compelling and worth playing, than virtually any of the surrounding "side" content. As an Elder Scrolls fan, it’s weird to be less interested in exploring and moseying across the world than in "solving" the main quest. Building on what it experimented with in the Knights of the Nine mini-expansion, in Shivering Isles Bethesda has added an immense new faction to the game and built the expansion around it.

And this isn’t an attempt to be crafty with my descriptions, either. You progress through the Court of Madness, gaining ranks within the society of the Prince of Madness, Sheogorath. To gain ranks, you’ll have to complete tasks for certain higher-ups within the society; as you gain ranks you’ll gain achievement points, just like in the core game’s other faction quest lines. What separates Shivering Isles from the rest of them (except possibly the excellent Dark Brotherhood quest line), is its expert craftsmanship. In Shivering Isles, the intimate intertwining of the storyline, the faction quest line, and the physical setting of the expansion make for an exceptionally executed RPG experience. You may have played something like this before, but not anything that’s this well-done.

Sheogorath, the daedric Prince of Madness (voice-acted and written with a flair for dark comedy that Terry Gilliam would appreciate) opens a gate to his realm in the "real" world, the Tamriel of Oblivion. You can wander into it anytime -- it’s not an invasion, but an invitation. The portal is a giant stone head, disfigured and grotesque. Hale souls go in, and broken minds come out. If you take the invitation, the very image of a proper renaissance-era seneschal interviews you in a small, dour chamber. Brick holds it together as much as the dreary gray pallor of the scene does.

When you’ve finished your interview with the man who is, actually, Sheogorath’s seneschal, the soul-crushing room begins to burn out and away, the stone turning to hordes of gloriously bright butterflies. It’s not the parts themselves that are exceptional, with butterflies standing in for Mania and the dour office playing the role of Dementia, but the crisp presentation and literally breathtaking reveal as the room melts away. Every step of the main quest emulates this wondrous opening scene, egging you onto the next step without ever feeling forced. Shivering even has a nice fake-out "big secret" that it reveals nice and early, a nod and a wink from the designers to their players that they know you aren’t going to fall for something that simple. It’s not "meta" so much as very well-written.

The scene leaves you (and the office’s table) in the middle of a realm that is half Technicolor fantasy and half Poe daydream. It’s easy enough to summate that one half of the land is Mania, a bright and poisonous place, and that the other is Dementia, a dour and grey place, but it’s impossible to understand how fresh and invigorating the setting is unless you play it. The tamest parts of the world are reminiscent of the wildest parts of Morrowind, with Golden Saints returning from that game in an appreciated nod to series fans.

Bethesda obviously took fans’ and critics’ complaints that Oblivion was too much a cookie-cutter fantasy affair to heart, because it’s created a world so bizarre but so organically right that it makes Tamriel all but impossible to return to. In fact, I wouldn’t step into the Shivering Isles’ gate until I was totally done with the content from the main game, because it’ll be rough going back to bandits and castles after you’ve fought an island’s semi-sentient eco-system and seen how a god of Madness builds his capital. Even the little things, in particular the micro-quests that citizens throw at you, are perfect for the setting. Quests like helping someone afraid of cats escape his Khajit best friend and helping a man die without having to commit suicide ("Have you seen the Hill of Suicides?"), are some of the best you’ll ever play.

While the Shivering Isles are big, reportedly a quarter the size of Oblivion’s playable province, most of the Isles aren’t worth taking a trip to. Sure, generic fantasy is boring, but fantasy this weird is stressful. Like the cliffracers in Morrowind (small, easily defeated flying enemies who were everywhere, making travel bothersome), the wilds of the Isles are full of clever ideas that don’t gel well. The biggest culprit here are the dungeons, which are more irritatingly random than intriguingly chaotic (I presume the design goal was the latter). The areas you’ll visit for the main quest line are a great primer, so don’t think you have to visit every inch of the map unless you really want to nail the thing.

The biggest issue is that there’s no option to make enemies level normally. Not that Bethesda ever mentioned one, but it heard us caterwaul about the bland Oblivion setting, so I’d honestly hoped it had caught this as well. Enemies level up as you do, insuring that you never wander into an area and meet a grisly death instantly, but also insuring you that have no chance to simply go into an old area and show those old low-level enemies that they should not have let you live. Or reload. This means no low-level enemies to practice your skills on, which makes it hard to raise a lot of core but passive combat abilities like block and armor. And there are plenty of user mods on the PC side that have some innovative solutions for this. Until Bethesda includes an option for players to face enemies who level normally (by genre standards), this is going to be a flawed game at the nitty-gritty combat and character generation level.

Those are largely quibbles, though. They are issues, but if you’re an RPG fan you’re definitely going to get your money’s worth here. If you’re not an RPG fan, consider watching someone who is play through the game just to see some of the psychedelic and beautiful things Bethesda has made. Although Oblivion’s playability hasn’t been improved, Shivering Isles storytelling and artistry simply soar beyond anything else the Elder Scrolls team has done. The focus on one storyline wouldn’t be enough to carry a full Elder Scrolls title, but this is a superlative effort for an expansion.