History Main / LockAndKeyPuzzle

In its simplest form, the player must do nothing more than [[MacGuffinDeliveryService bring the relevant object to the right place]] in order to solve the puzzle. Games with a more sophisticated user interface will require that the player use the "key" in some way specific to the nature of the puzzle, though in unskilled hands, this can lead to a GuessTheVerb puzzle.

* This was the closest thing there was to a puzzle in ''VideoGame/{{Doom}}''; there were three different keys (red, blue, and yellow, all three in "keycard" and "skull key" variants, but only one variant appeared per level), each of which opened matching-color doors within the same level. Which keys appeared (if any) depended on the level.
** Same with the earlier ''VideoGame/Wolfenstein3D'' and the later ''VideoGame/{{Quake}}'', both with gold and silver keys. Most of the mid-90's "Doom clones" like ''VideoGame/DukeNukem3D'', ''VideoGame/{{Dark Forces|Saga}}'', and ''VideoGame/{{Blood}}'' also copied this.

!!Examples

The LockAndKeyPuzzle is one of the oldest and most common puzzle types across adventure games, especially InteractiveFiction. Its advantages include a tighter coupling with the model world than the SetPiecePuzzle. The setup is also easy to couple with plot developments, using the "key" as a PlotCoupon. The major disadvantage of this puzzle type is the possibility of CombinatorialExplosion.

* There are at least two puzzle like that in {{Spellforce}}. While not mandatory, they offer nice loot. They reappeared in the sequel, as well.

* In ''VideoGame/TheElderScrollsIIIMorrowind'', there is an unmarked quest in the dungeons of Tel Fyr where the player would get a key and go looking through the tower and coprusarium for a series of chests that each contained some minor treasure and the next key in the line. Around the 8th chest, the treasures became very nice unique blunt weapons and the best Light Armor cuirass in the game.

* EternalDarkness has many of these puzzles. One notable example is the "Staff of Ra"-style puzzle where the character finds a rod and a lens, puts them together and places the staff on a pedestal. The sunlight (or whatever it is) coming from above focuses through the lens into a beam, which must be rotated to reveal reflective panels before finally unlocking the door.

The archetype of this puzzle design is [[LockedDoor an actual physical lock]]. The player must retrieve the corresponding key from somewhere else in the world, and bring it to the door. Another very common form is a non-player character who performs a task which [[EventFlag alters the state of the game world]] when he is given the [[GiveMeYourInventoryItem proper payment]].

* The ancient [[http://en.wikipedia.org/wiki/TinyMUD TinyMUD]] had a wonderful in-game language for constructing new puzzles. As long as they were lock-and-key puzzles. That was the only type you could build.

* The more plot-driven VideoGame/MysteryCaseFiles games all end with variations of this.

* In ''VideoGame/TheElderScrollsIIIMorrowind'', there is an unnamed quest in the dungeons of Tel Fyr where the player would get a key and go looking through the tower and coprusarium for a series of chests that each contained some minor treasure and the next key in the line. Around the 8th chest, the treasures became very nice unique blunt weapons.

* This one dates back to the dawn of Adventure: the goal of ''ColossalCave'' is to deliver the various treasures in the game to a treasure room.

* The NES game ''CastleQuest'' was one gigantic version of this.

* In the first Megaman Legends game, you had to find starter keys hidden in dungeons in order to drop the shield that housed the refractor. In the second to last dungeon you had to find ID cards.
* This was the closest thing there was to a puzzle in ''VideoGame/{{Doom}}''; there were three different keys (red, blue, and yellow), each of which opened matching-color doors within the same level. Which keys appeared (if any) depended on the level.
** Same with ''VideoGame/{{Quake}}'' and the gold/silver keys.

* LetsPlay/{{Raocow}} refers to these as "item babysitting" in ''VideoGame/SuperMarioWorld'' ROM hacks: finding a key and bringing it back to a lock you passed, finding a springboard and bringing it back to a high jump you passed, etc. He's not particularly fond of these puzzles, but it's about all the complexity and nonlinearity one can manage in the ''VideoGame/SuperMarioWorld'' engine.

* ''Franchise/{{Pokemon}}'' has at least two of these. In ''VideoGame/PokemonRedAndBlue'' and Yellow, plus ''VideoGame/PokemonFireRedAndLeafGreen'', you have to find the key card for the Team Rocket hideout to get through it. In ''VideoGame/PokemonDiamondAndPearl'' and Platinum, the key card is needed for the Team Galactic building.
* ManiacMansion is all over this. Finding all the keys (including keycodes), figuring out which lock they open, and getting things from the locked rooms comprises most of the game-solving puzzles

* The more plot-driven MysteryCaseFiles games all end with variations of this.

* {{Raocow}} refers to these as "item babysitting" in VideoGame/SuperMarioWorld ROM hacks: finding a key and bringing it back to a lock you passed, finding a springboard and bringing it back to a high jump you passed, etc. He's not particularly fond of these puzzles, but it's about all the complexity and nonlinearity one can manage in the VideoGame/SuperMarioWorld engine.