Zelda does lock and key puzzles very well and it's worth taking a little time to see exactly how it achieves this. We can apply the ideas and techniques we discover to our own games. Critically playing games you've enjoyed is a great way to tease out game design tricks to add to your game design notebook.
Lock Before Key
Repeat after me, lock before key.
Zelda gets the fundamental lock key rule correct; show the lock before the key. The screenshot below shows Link in the first dungeon, a point in the game when you cannot have access to bombs.
On the left of the screen there's an outline of a door with some cracks. This door can only be opened with bombs. What do you think the player will do when encountering this anomaly in the dungeon? Perhaps you remember what you did?
I remember trying to interact with the outline, thinking it was a secret door. I didn't know what was going on with this piece of wall. Unlike today, I didn't recognize this as a trope lock-and-key puzzle. I tried hitting it with the sword (the common player answer for any problem) and then I tried the lantern but nothing worked. In the end I gave up and continued on my way but the puzzle of the secret door stuck with me.
This doorway is a lock and it's shown before the key can be obtained. The player's brain is primed for any key that might fit this lock.
Later in the game, when I finally found the bombs, I immediately thought back to this door and then it became a self-directed quest to discover what was behind it. If the game gave me the bombs before I saw the door it would be far less satisfying to unlock this lock.
Showing the lock first gives three advantages:
- Foreshadowing - you're going to discover more about this.
- Challenge - opening this lock becomes a self-directed goal.
- Satisfaction - when you finally open the door you'll be satisfied because you've completed a goal of your own making.
A Trickle of Locks Instead of a Flood
In Zelda, we get a single mysterious lock first; the cracked walls. We don't encounter cracked walls, posts that need to be hammered down, boulders blocking the way, grappling points etc. A new player can only ponder so many mysteries at once without feeling overwhelmed and discouraged.
One single cracked wall is mystery enough to try and solve, if there were also posts, boulders and grappling points the first dungeon would be frustrating. There'd be more locks than keys.
Locks Hidden in Plain Sight
Zelda is littered with these small boulders, that you can see in the screenshot here.
Until Link finds the power glove the rocks are unremarkable. The power glove allows Link to pick up these rocks, revealing new pathways, caves, holes and items. What was previously background scenery now turns out to be a lock. There's something magical about giving a player that experience.
What could you hide in plain sight in your game (and then make significant later)?
More Than Just a Key
Bombs reveal secret passages behind cracked walls but what makes bombs an interesting key is their additional gameplay effects. They can damage enemies, they can damage the player, their action is delayed and they can be thrown. This makes them much more versatile and interesting than just a dumb key. Extra uses allow for more interesting puzzles.
Is there a key item in your game that could have additional uses? A party member as a key item maybe?
Leveled Locks and Keys
In Zelda bombs are introduced early on but eventually link discovers a seal his normal bombs cannot destroy. He needs the next level of bomb. At this point the player understands how bombs work and will know a better bomb can probably be discovered. Again this helps set up a self-directed goal - to discover the better bomb.
The Power Glove is replaced by Titan's Mitt allowing Link to pick-up bigger, heavier rocks. Again the player probably suspects this item exists and is on the look out for it.
Leveled items help extend the life of a game and still bring the player a lot of value. The only caution is to take care not to abuse leveled locks and keys. The first time you discover a rock too heavy to lift, even with a special item, that's an awesome discovery. If this occurs five times the player will soon tire of it.
In Zelda's case there are only two levels of bomb and glove and that's a good target.
- Introduce locks before the key.
- Drip feed locks slowly and steadily.
- A lock hidden in plain sight is an awesome experience.
- Keys with gameplay uses are better than keys without.
- Leveled keys and locks extend game life and are fun - if not abused.
Hope this brief look at how Zelda uses the lock and key puzzle gives you some ideas to apply to your own games!