Neverwinter Nights: Hordes of the Underdark is the second expansion for the role-playing game Neverwinter Nights. BioWare has created a dark and dangerous world of adventure set in the world of Dungeons & Dragons. Your hands are callused from many years of weapon play, your mind is sharp from hundreds of books studied, your feet are nimble from slipping unseen and unheard past thousands of guards and your faith is unshakable in the gods you worship... but will it be enough for this final terror? Will you stand once more for those who cannot? You are the last hope for the Forgotten Realms, you must face the unstoppable, you must decide the fate of all. You are a hero... but are you a legend? Epic levels, new prestige classes, new creatures, spells, feats, weapons and new tilesets to explore... endless adventure!

Neverwinter Nights: Hordes of the Underdark will include a new 20-hour single player campaign, designed for high-level characters and set amidst the famous city of Waterdeep and the foreboding Underdark from the D&Dr game's Forgotten Realms campaign setting. Hordes of the Underdark will significantly expand upon the Neverwinter Nights universe, most notably with the addition of Epic Level gameplay. Based upon the rules published by Wizards of the Coast in the D&D game supplement Epic Level HandbookTM, Epic Levels will be available for characters who have reached level 20, allowing them to advance as far as level 40.

In addition, Neverwinter Nights: Hordes of the Underdark will introduce several new prestige classes, including the Shifter, a druidic class specializing in shape shifting; dozens of new feats, such as Epic Reputation, Craft Weapon and Armor Skin; a multitude of new weapons and spells, many designed solely for epic level characters; challenging new creatures pulled straight out of the Underdark, including Mind Flayers, Beholders and Driders; several new character voice sets for even greater character customization; and 17 new epic soundtracks from composer Jeremy Soule.