Thursday, August 1, 2013

Procedural Lockpicking Revisited

A few years back I offered an idea of a way to make lockpicking more engaging and interesting for players.  You can go back and read that post here.  The problem was some of the things I say in the post (like traps at certain points in the flow chart) make it so locks would have to be designed individually, like mini-dungeons.  Way too much work for it to be used by me.  Zak posted a simpler method of guessing using dice and Arkhein did something as well using cards.

Both are sharp mini-game solutions to the problem of needing to make locks.  Unfortunately they don't allow for something else I'd like in a solution, a way that players can get to know locks and feel like they are gaining expertise, not just their characters through abstract level bonuses.  Today I offer another attempt at it.

First, if we limit the number of actions involved to 3 (I'll use Bump, Probe, and Rake) and limit the "tumblers" of each lock to 3, and even further, say that no action is ever used in a row, then we can whittle down the possibilities to something more manageable and discoverable.  If I'm not mistaken the possibilities for these constraints with actions ABC should be:
  1. ABA
  2. ABC
  3. ACA
  4. ACB
  5. BAB
  6. BAC
  7. BCA
  8. BCB
  9. CAB
  10. CAC
  11. CBA
  12. CBC
Now, if we limit the types of locks players encounter we can roll on that table to assign these combinations to give our different campaigns different lock solutions. So you might end up with something like this:
  1. Tin          CAC
  2. Copper   ABA
  3. Brass      BAB
  4. Iron        CBC
  5. Steel       CAB
  6. Strange  ACB
Strange locks are anything weird: crystal, organic, mythril.

The procedure to pick a lock is pretty simple, you try an action and if you get it wrong the lock gets stiff, letting you know that.  If your second attempt is correct you get to go on to the next tumbler.  If your second guess is also wrong the lock jams and will have to be smashed off.  Here is a handout you can use to record the lock solutions for your world and give to players to record their guesses:

As you can see, I've decided that each lock type will have certain number of hit points representing durability; how much damage you have to do to just break them off. I left the action names blank so you can put in what you want (I suppose I should have done the same for the lock types).

The challenge here is to balance the complexity a player will have to encounter in trying to pick a lock and the diversity of locks available in the world.  This depends a lot on how many locks you have in your dungeons and how lucky players get.  They might figure out Tin locks the first time they encounter them and know them ever after.  But they might not.  I think I'll have to just playtest this and see how it works.

I should probably leave it at that until I try it out but I have a few more ideas.

Modifiers could increase lock diversity without increasing the complexity of solutions too much.  Here's what I was thinking:

Lock Modifiers
  1. Cracked – more forgiving, first step, any action works
  2. Worn – more forgiving, first jam doesn't happen
  3. Normal
  4. Banded – Twice as many hit points required to smash it off
  5. Corroded – less forgiving, wrong action goes straight to Jam
  6. Spiked – less forgiving, each wrong action results in 1hp damage to the lock picker
More Locks
Because there are 12 possibile solutions on our chart you could also add 6 more types of locks of just duplicate the default 6 but call them Goblin locks (goblin tin, goblin brass, etc) or Dwarvish locks or whatever.

Character Level
This system doesn't take into account levels at all, you might assign levels to locks by rolling a d10. So, for instance, giving you a 7th level iron lock.  You might assigning penalties and bonuses from the modifiers chart like, locks above the picker's level act as if they are corroded or locks below your level act as if they are worn.  But that might get a bit fiddly.

I like Zak's suggestion that every level you get one get out of a jam free card, but only one.  That might be simpler.  Again I'll have to try this out and see how fast the lock types get solved.  If half the types are still a mystery at 5th level then level might not even be much of an issue-- actual player knowledge standing in for the assumed character's skill increases.


  1. I like this a lot. Thank you for sharing.

  2. I wonder if you could handle traps in a similar fashion, I'm sure it's do-able, I think this idea was very thought provoking and makes things a bit more fun for the Thief than just rolling dice and hoping it works.

  3. Thanks John, you might to it with certain similar traps, like poison needle traps or pressure plates. I think two things that make it a little difficult to use for traps is that 1) you would have to assume the player saw and new a trap was about and 2) traps can be very diverse like spears poking out or scythes swinging out, so any system like the one above might actually abstract traps more than just describing what players see and letting them tell you what they will try "We'll wedge a spike where the spear will jut out". But yeah, rolls for such dramatic, and important situations seem to suck some of the fun from the game.