Ultima Underworld is a series of two computer role playing games published by Origin Systems in the early 1990s. It is a spin-off from the successful Ultima series. The games were created by Looking Glass Technologies (originally known as Blue Sky Productions).
The gameplay for both titles is nearly identical. Both games are set entirely indoors, requiring the player to explore various dungeons and caverns. Progression is event driven and non linear. The player can explore and revisit areas at will and many obstacles encountered often have multiple solutions. Richard Garriott considers the Underworld series to be more action-oriented than the regular Ultima series.
The player views the game world from a first-person perspective. A point-and-click interface is used to interact with the game world. Items can be picked up and kept in the player's inventory as long as there is sufficient carrying capacity. Dropped items will persist throughout the course of the game. The game world is highly interactive. The player must be kept fed. Weapons and other items wear with use. Torches, for example, eventually extinguish after prolonged use, but can also be replenished with oil. Other examples of interactivity include using corn on a lit torch to create popcorn.
While many inhabitants of both Underworld games are hostile monsters, the player will also encounter more intelligent inhabitants who may be conversed with. The combat system is mostly focused on melee combat; ranged weapons are present but are limited in availability. Spellcasting is done by selecting an appropriate combination of runestones. There is a wide selection of spells, from offensive spells, such as fireball, to utility spells, such as night vision.