Opening Doors probabilities

[Starbeard]

Here's another quick table I've put together for my own purposes, and thought I'd share in case it proves useful to someone.

I used Anydice to figure out what the probabilities of opening a stuck door in x rounds were, based on how good you were at opening doors. Then I took these probabilities and made two tables: the first rounds these probabilities to a d100 roll, and the second rounds them to a coarser d20 roll.

The tables assume that you pick one person to open a door, and that this one person tries repeatedly until the stuck door is opened. Roll on the table to see how many rounds it took.

(edit: I have added a third table, which greatly rounds everything into a d6 roll)

docs.google.com/spreadsheets/d/12E-zKBZnlRU4-aJac3Td8auI9xeEhHd0cYsSUaBQ4_g/edit?usp=sharing

For my own purposes, I plan to use this as a fairly strict procedure in play by post games. The players state who is opening the door, and then I roll to see how long it takes: after 1 round no surprise is possible, and each additional round simply means more rounds to alert reinforcements or summon wandering monsters, etc., and that the door opener acts last in the first round of combat. Up to two others may assist in shoving the door, as long as their own ability is equal to or 1 grade less than the main character: doing so provides a +1 to the main's d6 probability.

So, someone who opens 2:6 is aided by two characters. One of them opens 2:6, and the other opens 1:6; both can help. The character's attempt is bumped up to 4:6. All supporting characters automatically go last in the first round of combat.

Conversely, one character opens 4:6, and all others in the party open 2:6 or 1:6. None of them can increase the chances, so no point in having them help.

[magremore]

Copied! Will also be really useful for solo dungeons/play-testing.

[Starbeard]

That's part of what I'll be using it for, definitely.

I've already started revising the tables. I had been using a streamlined algorithm that is accurate at the low end, accurate enough in the middle, and who's-going-to-notice in the very high, rare probabilities. They make for perfectly playable tables, IMO, that map quite neatly to combat rounds and exploration turns, which should speed up calculation.

But now I'm building a second set of tables, where I've actually gone through and calculated the exact probability for each possible outcome individually, for a somewhat less satisfying but more accurately modeled range of possibilities. For example, if you are rolling a 1-in-6 chance, if you roll extremely poorly you be waiting 20 or 30 tries before you succeed. Even that is a fudge: according to Anydice, the 98th percentile should be around 18 tries, the 99th should be around 26-30 and the 100th should be around 48 or something. There are too many individual possibilities in those ranges to map onto a single d100, so at some point you have to cave and apply some streamlined abstraction.

[Mordorandor]

Sept 20, 2022 12:36:27 GMT -6 Starbeard said:

Here's another quick table I've put together for my own purposes, and thought I'd share in case it proves useful to someone.

....

The players state who is opening the door, and then I roll to see how long it takes: after 1 round no surprise is possible, and each additional round simply means more rounds to alert reinforcements or summon wandering monsters, etc., and that the door opener acts last in the first round of combat.

....

(Are your rounds the 1-minute rounds or the 6-second rounds, or something else?)

If 1-minute rounds, like me, I conceptualize timing a bit like this:

1st attempt to force door open and gain surprise is fairly instant (1-5 seconds?). Because I have a hard time thinking a party can surprise someone on the other side if it takes 10-30 seconds (or more).

Let's say, the attempt starts at the top of the clock for the round. If successful, into the room the players go immediately, and if they surprise monsters that are in 30 feet, they can either take a half move to maneuver; use a spell, if there's line of sight; or resolve melee with no return blows.

But how much time goes by if the 1st attempt fails?

I also have a hard time thinking the party tries that first instant at surprise and, if they fail, goes about trying to open the door again for 50-60 seconds until at the top of the clock that starts the second round.

I'm inclined to say that after, like, the 1st attempt, the party makes it into the room in the first minute, no matter how many more attempts, but most definitely at the far end of that first minute.

[Starbeard]

Oct 16, 2022 20:14:01 GMT -6 Mordorandor said:

Sept 20, 2022 12:36:27 GMT -6 Starbeard said:

Here's another quick table I've put together for my own purposes, and thought I'd share in case it proves useful to someone.

....

The players state who is opening the door, and then I roll to see how long it takes: after 1 round no surprise is possible, and each additional round simply means more rounds to alert reinforcements or summon wandering monsters, etc., and that the door opener acts last in the first round of combat.

....

(Are your rounds the 1-minute rounds or the 6-second rounds, or something else?)

If 1-minute rounds, like me, I conceptualize timing a bit like this:

1st attempt to force door open and gain surprise is fairly instant (1-5 seconds?). Because I have a hard time thinking a party can surprise someone on the other side if it takes 10-30 seconds (or more).

Let's say, the attempt starts at the top of the clock for the round. If successful, into the room the players go immediately, and if they surprise monsters that are in 30 feet, they can either take a half move to maneuver; use a spell, if there's line of sight; or resolve melee with no return blows.

But how much time goes by if the 1st attempt fails?

I also have a hard time thinking the party tries that first instant at surprise and, if they fail, goes about trying to open the door again for 50-60 seconds until at the top of the clock that starts the second round.

I'm inclined to say that after, like, the 1st attempt, the party makes it into the room in the first minute, no matter how many more attempts, but most definitely at the far end of that first minute.

I figure it pretty much like you do. One-minute combat rounds and the first door check is effectively an instantaneous action, and if successful would allow normal surprise conditions, half moves, and all that; but if it opens and neither party is surprised then I will usually just start at the top of the round from there and let everyone take full turns, as if the door check took no time at all.

If it takes multiple tries to open, I don't have a definitively worded rule but I have typically handled it sort of like surprise segments or phases. Each attempt might represent a 10-second round segment (if I had to pick something), but each segment still allows normal combat movement from all parties; so the time scale shift is abstracted because actual combat round procedures stay the same. Typically these situations involve the defenders getting into position, or coming to reinforce or investigate, along with wandering monster checks essentially being used as hear noise checks for the denizens.

I admit that if there aren't so many rolls that I have to start considering the attempt as a special case situation, I would usually just fudge the total number of attempts up to a half or full round, and start the combat from there. That part is basically in the spirit of the B/X rules for time in the dungeon, where all combats take up an entire turn in the dungeon, no matter how many rounds they took.