I like lockpicking. I think it’s an interesting task that provides a great opportunity for rogue-types to provide benefits to the party in terms of stealth, safety in the case of traps, and it just fits really well into the fiction.
I love the image I have in my head of the rogue frantically trying to pick open the lock to the study in a manor while the rest of the party tries to distract the guards around the corner during the masquerade ball, each second that the rogue takes increasing the chance of discovery. Or of them leaned over deep in a dungeon working to get the service hatch open on a fire trap the party is backed up against while trying to fend off the hordes of undead they unleashed when they opened the mummy’s sarcophagus.
Unfortunately, I don’t like how lockpicking is implemented in TTRPGs. Generally, there’s two different ways that lockpicking gets implemented in games, with some variation. First, there’s the straight skill check. In GURPS this is the default way, you make a Lockpicking roll, take 1 minute for the attempt, and get some time knocked off how long it actually takes based on your margin of success. Other games do this a little differently, maybe they require a skill challenge where it’s three skill rolls, or they use a system like in the Index Card RPG and treat the lock as a challenge with health that you use your lockpicking skill to “attack” until it gives way. The other way is with a little minigame. There’s probably as many variants on this system as there are people who’ve played it, but a good example of this is available on Graven Utterance.
I don’t really like either one of these approaches, and for different reasons. The skill test approach depending on how the specific game implements it usually ends up being slow, utterly killing the opportunity to have suspenseful moments like I described above without using some external mechanic like a clock or countdown pool, and even if it’s not too slow to be used in these circumstances it still just boils down to “make a roll” either once, or every turn with no meaningful choice to be had by the player doing the lockpicking, which I find mechanically boring (whether or not the scene as a whole is narratively boring). On the other hand, the minigame version gives opportunity to be used in a time-pressured environment, but every implementation I’ve seen of it has one of two problems, either the GM must prepare or generate the key sequence for every lock separately, or the players get to learn a handful of distinct locks and just breeze through them because the same type of lock always has the same combination.
The Minigame
This left me with a hole in my games for a lockpicking minigame that enables suspenseful timescales, gives active choice with consequences to the lockpicking player, and which allows each lock to be different without GM preparation (which conveniently also enables solo roleplaying, another goal of mine). What follows is a description of such a minigame that relies heavily on the GURPS mechanics for skill resolution. I intend to devise another minigame or adapt this one in future to be system-agnostic.
To pick a lock the player must have an appropriate tool ready, and make a Ready maneuver to make a Lockpicking check. Roll an additional die after the check. If the margin of success of your Lockpicking roll is equal or greater than the number on the extra die, you have set the first pin. On a critical success, change the pin die to read 6. If you fail the Lockpicking roll or the margin of success is less than the number on the pin die, you may attempt again on the next round. If you do, you may choose after making the Lockpicking roll whether to keep the existing roll on the pin die, or to reroll it, keeping the new result.
Once the pin is set, set the pin die aside and move on to the next pin, until three pins are set. On the next round the player may make a Ready maneuver to roll their relative skill in Lockpicking, treating the sum of the numbers on the three pin dice as the base attribute. On a success, the lock opens. On a failure, the lock is in a false set. Remove the pin die with the highest number on it, and attempt to set the pin again starting from scratch. If the player fails to open the lock again after a false set has been made, the lock jams and cannot be opened.
If at any time, on any Lockpicking roll, the player rolls a critical failure, the lock jams and the player’s lockpicks break.
All the normal modifiers to lockpicking apply to every check in the entire process, so working by touch applies a -5, and the quality of a lock also adds to these checks, from +4 for cheap padlocks an everyday locksmith might be called out to pick, to +2 deadbolts on the average house or car, to +0 locks in basic home safes and on doors in well-secured homes, up to -5 on high quality locks on panic rooms or high security jail cells.
In Practice
Playing this minigame results in a wide range of times for how long it takes to get a lock open. In my playtesting I’ve gotten a lock open in 4 rounds when I rolled a crit on the first pin and succeeded every check after, and it’s taken upwards of 20 only for the lock to jam in other cases where I got a string of bad luck or the lock was high quality compared to my character’s skill level.
This minigame also shouldn’t fully replace single-check lockpicking rolls in your games. In low-stakes situations where you’re not working in combat time all these extra rolls just add tedium for no real benefit. Having both in the same game I think works out just fine too, since the minigame offers fast lockpicking under stress with a much higher chance of jamming the lock or breaking your tools, while taking the extra time to do the normal lockpicking checks means you’re careful with your tools and to not jam the lock.
But in those stressful situations where every second counts, I think this minigame should serve you well. It offers reasonable timescales for GURPS combat, and gives the lockpicking player some meaningful choices almost every round as they decide whether to set a pin immediately and have to roll against a lower score to open the lock and a higher chance of a false set, or to try for a higher margin of success not knowing how many rolls that might take.
Another thing to be aware of is how heavily this minigame favors relative skill (just how much can be seen later in The Math). This is because the relative skill of the user is what determines how likely you are to make the final Lockpicking check to open the lock. Having a low relative skill will massively increase how long the minigame takes, and the odds of a false set and a failure. What this means is that it’s impractical to try and Lockpick at default in adventuring circumstances. If a lock is better than a +4 lock (considered the default bonus for characters doing non-adventuring tasks), then the IQ-5 relative skill level is absolutely debilitating, even at high IQ levels. Once you reach supers level of intelligence of 25 or more, you’ll have better luck using the Haste penalties on a regular Lockpicking roll to complete the task instantly than you will with this minigame.
Examples of Play
Following are several second-by-second examples with each roll as it’s made to hopefully illustrate how the minigame plays. Some of these rolls have been adjusted to make these examples illustrative of the mechanics I wish to show off without becoming overly long.
Example 1
In this first example, the PC has an IQ of 10 and rolls Lockpicking at IQ, and the lock is a +0 lock. This would be a standard adventuring lock, like a home safe or a low security prison door.
Second 1
Player gets 11, failing by 1. They also roll the pin die and get 2.
Second 2
Player gets 13, failing by 3. They choose to reroll the pin die and get 6.
Second 3
Player gets 5, succeeding by 5. They choose to reroll the pin die and get 4. The
first pin is set.
Second 4
Player gets 12, failing by 2. They roll the second pin die and get 5.
Second 5
Player gets 9, succeeding by 1. They choose not to reroll the pin die. The
margin of success of 1 is not sufficient to set a pin die value of 5.
Second 6
Player gets 8, succeeding by 2. They choose not to reroll the pin die.
Second 7
Player gets 6, succeeding by 4. They choose to reroll the pin die and get 4. The
second pin is set.
Second 8
Player rolls 12, failing by 2. They roll the third pin die and get 5.
Second 9
Player rolls 9, succeeding by 1. They choose to reroll the pin die and get 3.
Second 12
Player rolls 13, failing by 3. They choose not to reroll the pin die.
Second 13
Player rolls 7, succeeding by 3. The third pin is set.
Second 14
The player now rolls to open the lock using a Lockpicking check against an
attribute of the sum of the pin dice, so 4 + 4 + 3 = 11. The relative skill
level of the player is +0, so this is unmodified. Player rolls 14, failing by 3,
and the lock falls into a false set. The player removes the highest pin die.
Second 15
Player rolls 11, failing by 1. They roll the pin die and get 4.
Second 16
Player rolls 6, succeeding by 4. The pin is set.
Second 17
The player must now make the final Lockpicking roll to see if the lock opens or
jams, since a false set has already occurred. The sum of the pin dice is 11
again, and the player rolls 13, failing by 2, causing the lock to jam.
Example 2
In this example, the player has an IQ of 12 and rolls Lockpicking at IQ+1, for a total of 13. The lock will still be a +0 lock.
Second 1
Player rolls 4, a crit success, and sets the pin die to 6 regardless of what
they would have rolled.
Second 2
Player rolls 9, succeeding by 4, and rolls a 4 on the pin die. The second pin is
also set.
Second 3
Player rolls 12, succeeding by 1, and rolls a 3 on the pin die. This is not
enough to set the pin.
Second 4
Player rolls 10, succeeding by 3. The player chooses not to reroll the pin die,
and it sets at 3.
Second 5
All the pin dice are set, and the sum totals 13. Because the player rolls
Lockpicking at relative level +1, this makes 14 the target. The player rolls 10,
succeeding by 4, and the lock opens.
Example 3
For this example, the player has an IQ of 12 and rolls Lockpicking at IQ+1 again. The lock this time is a -2 lock, representing an above-average adventuring lock, like a medium security prison lock or a well-crafted lock on a trap’s access panel. This makes effective skill 11.
Second 1
Player rolls 9, succeeding by 2. The pin die rolls a 4. The margin of success is
not sufficient to set the pin.
Second 2
Player rolls 16, failing by 5. They choose not to reroll the pin die.
Second 3
Player rolls 6, succeeding by 5. The player chooses not to reroll the pin die,
and it sets at 4.
Second 4
Player rolls 12, failing by 1. The second pin die rolls a 5.
Second 5
Player rolls 8, succeeding by 3. They choose to reroll the pin die and get
another 5.
Second 6
Player rolls 11, succeeding by 0. They choose to reroll the pin die and gets
a 1.
Second 7
Player rolls an 18, critically failing. The lockpicks break in the lock and it
jams.
The Math
I’ve done a little math to try and see how the odds of picking a lock using this minigame compares to the odds when just making a single lockpicking roll. I’ve assumed that each pin value will be the mean of the margin of success (capped at 3.5 for the average of a d6 roll, and accounting for crit successes setting the pin die to 6) when you succeed at the roll, and that to successfully open the lock you must succeed at that roll within 2 attempts, to represent the possibility of a false set (whose expected resulting pin value is the same as the original pins). This is combined with the odds of never crit failing among the average number of checks required to complete the minigame.
The average number of checks to complete the minigame I’ve calculated to be the weighted average by the odds of succeeding the final lockpicking roll between 3 times the number of rolls to set a pin plus 1 and 4 times the number of rolls to set a pin plus 2 to account for a false set. The number of times to set a pin is the reciprocal of the odds of getting a margin of success equal to or greater than the mean margin of success under the same restrictions as above.
All the testing I’ve done at various attribute, relative skill, and circumstance penalties (like lock difficulty) show that this method is highly sensitive to the relative skill and much less sensitive to the attribute of the character compared to a single check, and this is expected since the final chance of succeeding is based on the average expected value of a pin die and the character’s relative skill.
It seems that the minigame is about 10-40% less likely to succeed relative to a single check if working at a relative skill of +0, and up to 60% less likely at relative skill -1. On the other hand, at relative skill +1, the minigame is only very slightly less likely to succeed, usually less than a 10% difference. At relative skill +2 and higher the minigame is actually slightly more likely to succeed until very high attribute levels of 14 or more, at which point the difference is still low. This difference decreases at relative skill levels of +3 or more.
Because of how much difference relative skill makes compared to attributes, and circumstance penalties effectively emulate reducing relative skill, this heavily penalizes anyone without high relative skill if they want to make an attempt at higher difficulty locks or under worse circumstances. Personally, I’m good with this since I think specific dedicated skill with the particular task makes more difference than high attribute values when operating under pressure.
I suspect that the actual expected value of the pin dice will skew higher than my math says because of players strategically choosing to roll for longer to get higher margins of success. If I skew the expected value 0.5 higher per pin die then the odds of success seem to match much closer, generally staying within + or - 10%, and trending towards -40% or worse with extremely bad relative skill. If you wanted to adjust for this and make the minigame about 40% less likely to succeed than the usual method until the player gets to high relative skill you could apply a -1 penalty for operating under stress or something, but honestly I probably wouldn’t bother with this as I think that’s a bit too punishing.
The average amount of checks it will take to resolve the minigame is the one aspect of the game that is strongly affected by effective skill and not just by relative skill, though that does still affect it by changing the likelihood of a false set. It ranges from about 22 checks at effective skill 10, down to about 10 checks at effective skill 13, down to about 7-8 at effective skill 20. When effective skill is reduced below 10, the time to complete starts to blow up, and reaches over 60 checks at a relative skill of 7, at which point the normal method of resolving Lockpicking becomes advisable.
The number of checks it takes on average has the greatest impact on whether or not there will be a critical failure at some point during the minigame. This ranges from a 33% chance of critical failure when operating with an effective skill of 10, to a 15% chance of critical failure at an effective skill of 15, with massively diminishing returns beyond that. Below effective skill of 10 the chance of a critical failure skyrockets as well, with a nearly 45% chance of critical failure at 9, and passing a 75% chance of critical failure at 7.
Of course because of how many rounds it would take to set a single pin with such a low effective skill, it’s extremely likely that the players would give up and choose another course of action long before their chances of a critical failure would go that high.
Adapting this to Other Tasks
I think you could pretty trivially use this same system for science-fantasy hacking with just a little reflavoring too. Or disarming traps, repairing a vehicle, dispelling a magical ward, or any number of other tasks that you want to be mechanically interesting when doing the task under the pressure of combat time that shouldn’t be accomplished in just a few seconds.
Adapting this for Other Systems
As mentioned above, I intend to make an actual minigame which resolves the same issues this one does for other systems, but there’s a few specific issues that I have with this specific minigame for other systems, and some first-blush thoughts I have on resolving these issues.
First, rounds in GURPS are one second long. It’s expected that on any given round you’ll make 0-1 rolls unless you’ve got something specific that grants you multiple attacks, or you’ve crafted something complex with advantages. The spread of 4 to >20 rounds for how long it takes isn’t too bad. If you were to use these rules directly with other games with a longer time-scale for a round, e.g. WOiN, or the world’s most popular fantasy TTRPG, where 10 rounds make one minute making one round approximately 6 seconds, that makes this approach untenable, because it just takes too much time.
There are ways that this could be mitigated. Perhaps you make more than one lockpicking check per round. If your game system has a multi-action system like WOiN or Pathfinder 2e (though that game has fast lockpicking so maybe this minigame is unnecessary), maybe you can make one check per action spent. This would put the length of time somewhere in the range of 2-7 rounds in the case of Pathfinder, and 2-10 in the case of WOiN. This is maybe acceptable. The speed of the system also depends on how much you can exceed a lock’s DC by.
Second, the resolution mechanic in GURPS is pretty unique as far as I can tell compared to other systems, and this makes the whole idea of creating a new stat you roll against with the pin dice kinda weird.
Exactly how you adapt this would have to depend on the specific game, but for roll-over DC games, maybe you could make it so that instead of standing in for a stat, the sum of the dice stand in for a die roll? The range 3-18 is relatively close to a d20, so this could work for some d20 games, although it may make it hard to keep players in the dark about whether they’ll get a false set. For WOiN I might think to interpret the sum of the dice as an attribute, then use that attribute pool with your lockpicking skill.
The quality of a lock in some games could also play a more interesting role than just setting the DC or adding a modifier. It could mean a different size of die used for the pin die, offering a narrower or wider range of values. What the default is could be adjusted away from d6s as well depending on how much a check is likely to exceed a DC by.
For num-successes dice pool games, perhaps the pin die can be a d4 by default, and the roll specifies how many successes are required for that pin, and perhaps you need a number of successes equal to (12 - sum)/3 + 1 for the final check to open the lock or fall into a false set.