LEVEL DESIGN: KEYS

Keys are a really interesting part of non-linear level design, and a great tool for helping players understand the world around them. This post will focus on the basic attributes that keys possess, and then go through a quick example of how these concepts work together in Demon Crush! So, how do keys work, on a mechanical level?

When we made Demon Crush, we used two separate attributes to define keys: “Durable/Consumable“, and “Pure/Ability“. Any key can be either durable or consumable, and any key can be a pure key or an ability key. There may be other attributes, or completely different ways to look at keys, but this is how we viewed them for Demon Crush:

  • Durable: A durable key can be used any number of times on whatever kind of door it unlocks. For example, a Level 1 Keycard in the Metal Gear/Metal Gear Solid series will open every Level 1 locked door in the game. When you have the Level 1 Keycard in your possession, all level 1 doors in the game are effectively unlocked, because the Keycard is durable; it has no limit to the number of times it can open a door.
Keycards in Metal Gear/Metal Gear Solid are pure and durable.

Keycards in Metal Gear/Metal Gear Solid are pure and durable.

  • Consumable: Keys in The Legend of Zelda are consumable; although a key can unlock any door in the game, it can only do this one time. After that, the key is used up and the player will need to find another one to open the next door. But that’s just the keys that look like keys; players might not realize it, but bombs are consumable keys, too. Aside from their use as weapons, bombs can open secret passageways, sometimes even giving the player a path around a locked door. This means that having multiple types of consumable keys can offer the player a choice of which route to take next, but require them to commit resources to that choice. Consumable keys, combined with this type of level design, can thus become a resource that the player can stockpile and manage.
Regular keys in The Legend of Zelda are pure and consumable. Bombs also act as consumable keys, but are ability keys instead of pure due to their use as weapons.

Regular keys in The Legend of Zelda are pure and consumable. Bombs also act as consumable keys, but are ability keys instead of pure due to their use as weapons.

  • Pure: A pure key has no use other than being a key. That is, the player cannot use the key for any purpose other than accessing whatever the key is meant to unlock. The Blue Crystal in Castlevania II: Simon’s Quest is an example of a pure key, even if it doesn’t actually look like a key. With this crystal, Simon can lower the water level of a certain lake, allowing him to travel across the land through a cavern that that would be otherwise be flooded and unusable. However, the crystal has no other use; Simon doesn’t gain any power that could be used in any other situation.
The Red Crystal in Castlevania II: Simon's Quest is a key, despite not appearing to be. It has the pure and durable attributes.

The Red Crystal in Castlevania II: Simon’s Quest is a key, despite not appearing to be. It has the pure and durable attributes.

  • Ability: Unlike a pure key, an ability key is actually a player ability that doubles as a key by letting the player bypass or overcome an obstacle in addition to being generally useful. In Metroid 3: Super Metroid, every key is an ability key. The Morph Ball permits Samus to roll into small gaps, so she can reach places that would otherwise be inaccessible. Missiles blow open red door seals. Bombs can destroy certain types of blocks that are impervious to her beam cannon or missiles. But every one of these items has another use; rolling into a ball helps Samus to avoid enemy attacks while remaining mobile. Missiles can destroy tough enemies quickly and are vital in boss fights. Bombs can reveal optional hidden passages in the environment, and give Samus a last-ditch defense and some interesting mobility options while rolled into a ball.
As a key, the Morph Ball in Metroid has the durable and ability traits.

As a key, the Morph Ball in Metroid has the durable and ability traits.

Now that we know what they are, let’s look at a typical gameplay loop that uses them. The player finds a barrier they can’t pass or a treasure they can’t collect, and they need to walk past, or go another way. On that path, they expect to find some kind of key at some point, and come back to unlock the barrier or collect the treasure. Since the player has already seen the lock before finding the key – or possibly even knowing exactly what the key is – the game creates a little mystery, and gives the player a medium-term goal. It also prompts them, subconsciously, to make a mental note of where they need to return after they have the key, incidentally memorizing a little bit of information about the game world. As they travel around, the barrier or treasure may fade from their mind, but then, when they stumble upon the key, they remember it. Finally, upon returning to the place with the lock, they feel a rewarding sense of accomplishment as they use the key and claim their prize, whether it’s a new power, an area to explore, or progression in the story line.

When we look at keys in an abstract sense, we can find them in a variety of different games, and in different forms. In The Legend of Zelda alone, we can find:

  • Durable pure keys: The Magic Key, the Triforce, the Raft, the Power Bracelet
  • Consumable pure keys: Regular Keys
  • Durable ability keys: Candles, the Recorder, the Ladder
  • Consumable ability keys: Bombs

…And it’s possible we missed some. For example, some people might argue that the Silver Arrows are a key, because they are required, but fairly easy to use against the final boss. We did not list them, because there is still some element of skill; not freezing up when Ganon is stunned, and remembering to pull out and use the arrows is part of the battle. If Ganon were stunned indefinitely and could not recover and continue fighting, then we would consider the Silver Arrows would be a consumable ability key. (For those who enjoy this argument, you can apply similar reasoning to many weapons in the Metal Gear/Metal Gear Solid series; sniper rifles and guided missiles come to mind.)

Just for fun, an assortment of keys that aren’t labeled as keys in other games:

Sekiro: Shadows Die Twice: The Mortal Blade is a durable pure key; it would be an ability key, due to its associated Combat Art, but the player does not actually have to use the Combat Art at any point in the game. For contrast, the Mibu Breathing Technique is a durable ability key, because the player has to use it, not just acquire it.

Jedi: Fallen Order: Every Jedi ability Cal remembers is a durable ability key, since they all have applications other than just accessing new areas. Every upgrade BD-1 receives (except for slicing damaged droids) is a durable pure key, since they are (generally speaking) trivially easy to use and do nothing other than grant access to areas or items.

The Last Of Us: Shivs are consumable ability keys, because they can be used to open locks or kill enemies, but break from either usage.

Dark Souls: The Lordvessel is a durable pure key. It is not an ability key because, although the teleportation ability it grants is required to exit the boss arenas that it unlocks, teleportation is a non-gameplay menu feature rather than a character ability that can be used during normal gameplay. If the Lordvessel granted something like a teleport-dodge move that could extricate players from boss arenas and also had a combat (or other skill-based) application, it would be a durable ability key.

As you can see, an abstract concept of what “keys” are can give designers a broad array of tools to use when building games. We can purposely link character abilities with map progression. We can create deliberate sequence breaks by allowing high-skill players to pass through difficult areas early in the game, that most players will easily traverse much later with an item they have acquired. We can guide a player around an area to help them learn the map or give them an understanding of the narrative elements of our world. We can inspire curiosity and the excitement of discovery. We can even use keys to hide secret areas or upgrades in plain sight, rewarding players who observe and remember details about the world. Keys are powerful and versatile, and we can tap into their potential by thinking of them in abstract terms. You can find them everywhere in games, very often including games that pretend not to have them at all!

Categories: Design

0 Comments

Leave a Reply

Avatar placeholder

Your email address will not be published. Required fields are marked *