Key

A red key in Catacomb 3D.

Keys are critical items used in navigating the world in Catacomb 3D and the Catacomb Adventure Series.

They have the same purpose (and share the same sprites) in all four games.

They come in four colors: Blue, Green, Red, and Yellow. The player uses them to unlock doors of a matching color. Each key can only be used once, though a player can pick up multiple keys of the same color. Once a door is unlocked, it vanishes, along with the key used to unlock it, allowing the player forward (unless it's the level exit, in which case it loads the next level).

Finding one or more keys is often important to completing a level in all four games.

Trivia

• There are several doors in Catacomb 3D that can be unlocked, but have no matching key. These can be unlocked with cheats, but mostly just unlock shortcuts that lead to a place that the player can easily access anyway. The most obvious example of this is in Ground Floor, which has a Red door but no key.
• It is occasionally possible to leave a level before using all of its keys, in which case you will carry them into the next level. In a few cases, this can be used in deliberate and amusing ways (such as skipping Nemesis entirely in Catacomb Apocalypse).

Catacomb 3D
Characters:	Petton Everhail - Grelminar - Nemesis
Enemies:	Orcs - Trolls - Bats - Mages - Demons - Fireballs
Items:	Magick Missile - Cure Potions - Treasure Chests - Keys - Bolts - Nukes - Scrolls - Gates