The mechanics of Ladders/Holes

Riverspoke

Tiller
General question.

When traversing in the Mines and Skull Cavern, we need to make ladders or holes appear in order to descend. To do this - unless there is already one uncovered - we need to break rocks, or kill enemies.
I was wondering... Are the positions of ladders/holes predetermined each time we arrive at a floor, or is there a coded percentage that a ladder/hole appears every time we break a rock?

- If the former is true, traversing the dungeons is a game of "find the ladder/hole".
- If the latter is true, our best strategy would be to immediately break as many rocks as we can.

Until now, I assumed the latter. But I wanted to make sure, so I amend my spelunking strategy.

Sorry if this is a noob question.
 

Elenna101

Farmer
It's... sort of both, actually?

Basically, the way the code is written, the intention is that each rock has a certain probability of uncovering a ladder when broken. However, the RNG in this game is often very predictable. If you know the location of a rock, the floor it's on, and the game seed (the number in the game's save file, in 1.5 you can set the seed to a specific number when you create the game), then you can predict whether that rock will give a ladder.
So although it's intended to be a percentage chance every time you break a rock, in practice you can create a grid showing which location will give a ladder, and then you just have to find one of those locations that happens to have a rock on it and break that rock. This would be very hard to do by hand, but if you're interested @BlaDe has a predictor app (found here) which will let you see ladder locations (among other predictable things).

Incidentally, the probability of getting a ladder from a rock increases as the number of rocks on the floor goes down (or you can think of it as new ladder spots appearing as you break more rocks) - if you have only two rocks left on the floor and there's no ladder yet, the next one that you break is guaranteed to give a ladder.
Killing all enemies on the floor also increases the chances of getting a ladder, and so does having a higher daily luck and increasing your luck buff.
It's also worth noting that killing enemies has a 15% chance of getting a ladder, which is usually higher than the chance from rocks. However, killing enemies often takes more time than breaking a bunch of rocks. So you have to think about how quickly you can kill the enemies (and also whether you want their drops).

In terms of mining strategy, keep in mind that if there's a random free ladder on the floor when you enter on the floor, no more ladders can spawn from rocks, although you can still get ladders from enemies. So you don't necessarily want to just go in and start breaking rocks willy-nilly, because you could be wasting energy and time when there's a freebie off screen. But you also don't necessarily want to walk around the whole floor to look before breaking rocks, because that also wastes time.
In single-player on PC, one (rather tedious) options is to pause and take a screenshot so you can look at the whole floor and check for ladders. If you aren't doing that, you have to find a balance to be found between walking around and breaking rocks.
(Incidentally, if you get one ladder from a rock, that also prevents other rocks from giving ladders. Getting ladders from monsters won't prevent you from getting other ladders, though.)

Note I said "random free ladder" in the last paragraph. Ladders that are always there (e.g. the ones on treasure floors in Skull Caverns, or at the end of floor 12, the long one with the minecart at the end) don't block other ladders from spawning. In fact, it's often a good idea to break rocks in Skull Caverns treasure floors even though there's a free ladder, because it doesn't take much time to break all of them and you might get a drop shaft.

Speaking of which, the above is all just how ladders spawn. The holes in Skull Caverns are pretty simple - every time a ladder spawns there, it has a 20% chance of turning into a hole instead.
 

Riverspoke

Tiller
Thank you so much, Elenna101, for taking the time to answer my question so thoroughly and for the tips. You are better than the game's wiki and you quite literally illuminated my Skull Cavern of ignorance! Taking all of this into account is sure to amend my strategy of future trips to the dungeons. Cheers!
 
Everything Elenna said is spot on!

I would like to add that getting a dropshaft does not prevent other rocks from dropping ladders/shafts. Once you get a ladder though, that is it, no more ladders/shafts from rocks.
Is that true on all platforms? I play on Xbox and do regular bomb rush mine methods and often see 3-4 ladders while I am either looting or dealing with mobs as the bombs seem to do low damage. 8 to kill a green slime on level 20+ so there is reasonably no overlap between mob spawner ladders vs rock spawned

Playing on console Xbox one
 

imnvs

Local Legend
Is that true on all platforms?
Monster stairs don't prevent rock stairs. When rock stairs spawn, there is a chance they could instead be drop shafts which don't prevent further rock stairs. As soon as you get a rock stair that is a stair and not a drop shaft, though, you're done getting rock stairs but can still get monster stairs.

...and this should be true on all platforms.
 
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