In terms of gameplay, HoN is a typical dungeon crawler: light on story, heavy on combat, and with a little bit of exploration thrown in. Built around a central quest hub (the city of Neverwinter), players are able to easily restock between adventures, and can choose from a range of level appropriate adventures.
Combat is quite faithful to D&D, and includes line-of-sight mechanics and a wide range of abilities. Like many adventure RPGs, the player controls a party of adventures either directly, or with the aid of AI. Combat is of course turn-based, and many abilities are limited to once-per encounter, giving fights a tactical edge.
While there is an exploration aspect to the game, it is quite limited. Dungeons will have optional rooms, and on rare occasions these rooms will sometimes require some exploration to find. For the most part though, the game follows a simple pattern: enter room, kill everything, collect loot, choose a direction, and repeat.