There's good rules for large creatures Squeezing if they need to fit into a corridor that's only designed for a medium creature. But what about if on a thin bridge?
6 inches wide is a bit of an effort for a laden medium creature to walk down, but large? Feels quite a bit more of an effort.Yes, larger creatures tend to have lower dex, but the actual reduction is fairly small.
I'm less after "Here's how I'd house rule this..." and more after whether there are any existing rules or guidelines that I've missed?
About the only one I can think of is an that an argument could be made that a large creature has to squeeze into medium wide in order to make a try at the thin bridge?
Doesn't the Acrobatics skill already cover $#!+ like uneven terrain, narrow ledges, and slippery ice? Balancing and all that?
It does. What feels a bit weird to me is that a large creature has a specific penalty to hiding - beyond any dexterity penalty it might suffer. But none to this particular bit of acrobatics.
I'd say a larger creature shouldn't suffer extra penalties than a smaller creature for uneven terrain or slippery ice - because it can still spread itself. The tendency for bigger creatures to be more ponderous is covered by the dexterity penalty.
However if the check is to get across specifically narrow terrain (the table with 1–3 feet/7–11/2–6/Less than 2 inches wide) then it feels like firstly, there's definitely a point a Tiny creature doesn't make a check, a Huge or Gargantuan creature can't do it… but that point isn't stated.
But also there's a point beyond that "Nah, that's just ridiculous!" where it should be quite a bit harder (like it's harder to Stealth whilst large) without being impossible.
I suppose it's probably one of those rules that falls between the cracks - stealth comes up a lot, so "Size affects stealth" comes up. Balancing on narrow bridges, ledges or similar comes up much less often, so the ability of a larger creature to do so is less important for the rules to be able to model accurately.
I think the main issue is that a larger creature is inherently a bigger target and is easier to see. That's just how things are. A larger creature is not inherently less acrobatic, agile, or balanced (despite a Dexterity penalty assessed to all such creatures, which you've already stated you aren't considering).
There are too many vastly different physiologies in large creatures in the real world, let alone a fantasy game to base everything on such an ambiguous rating (a Large snake has vastly different dimensions than a Large-size horse or a Large-size gelatinous cube).
(Continuing, since site crashed and I couldn't edit)
Just being Large isn't an indication of clumsiness. Any individual creature would be better served by having a racial penalty to Dex (above any size changes) or a penalty to Acrobatics to account for such things, rather than just being based on something as subjective or anomalous as the space it takes up on a grid-map.Not unlike a GM ruling that a Large or Huge-sized serpent doesn't have a Squeezing penalty to movement to slip down a narrow corridor. It's a fair ruling based on creature specifics instead of a generality.
And yet, Fly inflicts such a penalty based on creature size alone - ignoring the specifics of its physiology. Albeit, it does so at half the rate that Stealth does.
Thus I'm inclined to believe that the rules-writers were willing to put in size based changes for entire skills, but not for relatively niche sub-uses of that skill.
Were I inclined to house-rule, I'd use the table from fly (+/- 2 per size category, rather than the 4 from stealth), and at that point a well-trained elephant could still walk a tightrope. (I believe it's rather cruel and painful for them, however!)
But I tend to run a pretty 'by the book' game where I set a difficulty and the PCs have to rise to it - I make rulings (and discuss them with the players) where there's actual gaps in the rules. But this? It's just, no, there's not a modifier. And given the situation won't be a collosal creature atop a 5cm beam, I don't need to make a "That's ridiculous!" call.