Released in the same year as Shadows of Undrentide, Hordes of the Underdark manages to be more interesting than both the former and the original campaign, which is probably a first as far as game expansions go. Following on the rather momentous ending of SoU, Drogan’s Pupil–yes, this time, you’re specifically meant to play with the same character, especially since this expansion is designed for higher levels–manages to escape from the Plane of Shadows, where s/he had escaped to, and ends up in Waterdeep, a city to the south of Neverwinter. Waterdeep is having its own problems. It’s located above Undermountain, a labyrinthine dungeon built by the mad Wizard Halaster in an old mine, as a test of mettle for adventurers. However, Undermountain also provides an entrance to the Underdark, the huge underground area that’s home to such unsavoury creatures as drow (Evil elves), duergar (Evil dwarves), beholders (giant eyeballs) or illithid (Cthulhu-like creatures that like to vampirise people’s brains). As luck would have it, the drow are currently headed by a Matron Mother who calls herself the Valsharess (i.e. Empress). After carving her way through the other drow houses, she has decided that it’s time for her to invade the surface world. For this purpose, she has managed to acquire the services of none other than Mephistopheles, the lord of the eighth plane of Hell. A group of Good drow led by the Seer, a Cleric of the drow goddess of the Moon, Eilistraee, is trying to oppose her, but they’ve not had much luck so far. So the drow are starting to make incursions on Waterdeep through Undermountain, and the city has issued a call for help, which is where your character comes into play.
As SoU did, HotU also adds a bunch of new Feats, Skills and spells, but gameplay otherwise remains much the same. Teleportation is still possible, with the novelty that you can now set bindings for the artefact that your character uses to teleport (called the Relic of the Reaper, which s/he found on the Plane of Shadows where s/he escaped at the end of SoU). Moreover, as long as you have a Rogue Stone in your possession, your character is essentially immortal: getting K.O.’ed will use up the stone to transport them to the Realm of the Reaper, where a mysterious creature called the Reaper will simply send her/him back where they came from.
The main addition is that you can now have two henchmen in your party, allowing them to interact with each other as well as your character, which really helps to flesh them out. Wizards and Sorcerers are really in luck here, as they will also eventually have the possibility of building their own golem. Add to that a familiar and a summoned creature, and they can end up with their own personal army. Three romance options have also been added, including the tasty treat known as Valen. There are also six more prestige classes to choose from.
HotU also makes an effort in terms of antagonists, as both the Valsharess and Mephistopheles are far more memorable and charismatic than Morag, Maugrim or Heurodis could ever hope to be. There are also other possibilities for dealing with them than simply duking it out, which brings some welcome diversity to the table and actually hearkens back to Planescape: Torment, which can only be a good thing when it concerns anything other than combat. However, in order to have the possibility to take advantage of these options, your character needs to SAVE THEIR MONEY. Trust me when I tell you that they will need every last penny by the end of the game (two or three million at least). Sell stuff early, preferably in Chapter 2, because Chapter 3 doesn’t have good opportunities for making cash from sales, and avoid selling stuff to the genie when you come across him. You won’t be sorry you did, as it will also add options for helping your henchmen with their personal issues.
One thing that HotU unfortunately doesn’t improve upon is the music: it’s still as featureless as in the OC and SoU. But don’t let that deter you: this is a very good expansion, going a long way towards correcting the game’s flaws. The story is far less convoluted, which makes the stakes that much more relatable. The characters are good–except for Aribeth–, some of the new prestige classes are awesome, and the sidequests are interesting. So, in my opinion, if you want to get the best out of NWN, skip the OC altogether and just make a character for SoU and HotU. You won’t miss out on much (except the backstories for Aribeth and the OC henchmen, which are minor details) and may enjoy yourself a lot more without having to slog through the OC.