Still not seeing an issue with either of those (even if they existed). You describe the situation, PC has a relevant feat and uses it, happy days!
In fairness, not all of those are feats. With the Waterfall, there's an Athletics check to do so. If you can beat a DC40 Athletics check, you can indeed start swimming up a waterfall.
But really, those things are player-facing powers, where the player has to know it more than the GM. You don't get damaged from stuff based on smell? Well, that's on you to tell me. Though I think these examples aren't great. Why not go with:
"Oh, I have Smell as an imprecise sense, which means I can actually move an undetected creature to hidden just based on smell!"
(That sounds complicated, but it's just that while other people might notice a bad smell in a room, you can basically narrow down where that bad smell is likely coming from. The big thing is that, at close range, you can potentially identify hidden creatures with your nose, even if they are invisible.)
This one would be more of an issue, because it requires the GM to come up with the number of pebbles in the room, despite that not being particularly useful information for anyone. I agree that would not be great design, but since by your own admission you made it up, I concur with
@Justice and Rule's challenge: How about some
real examples?
_
glass.
The only one I can think of that got discussed in one of the previous discussions was the opening feat from the Dandy archetype about being able to, as an individual, spend a day to influence a rumor as a downtime activity. I don't see that as a huge deal, to be honest, but it's the one feat that I feel like even resembles what is being talked about.
Instead, most feats are, indeed, exception-based: they create exceptions for the player, whether it be through specialized actions, less restrictions for certain actions, etc. I always bring up
COMBAT CLIMBER~! because I think it's actually a really good example of a small but neat little feat.
Unlike 5E, where beyond movement speed climbing is largely about rulings in what you can and can't do, there are specifics to PF2's climbing. There are checks for speed, but also you have to have both hands free and you're flatfooted while climbing, unless you have a climbing speed. This tells your players two things:
- If you climb, you're going to be extra vulnerable, since you won't be able to have weapons or shields at the ready, as well as having an effective -2 to your AC.
- Having a climb speed is a huge advantage. Spider Climb and things that can grant Climbing Speeds are a real boon to strategy.
To me, these are big things. Not only do the players have a solid idea of what I'm going to tell them before they attempt climbing something (instead of having a discussion and hashing out how I'd rule), but there are avenues in which their individual feats can start to come into play.
COMBAT CLIMBER~! obviously allows a player to be able to climb with a weapon in-hand and also are no longer flatfooted. Someone with Quick-draw can pull out their weapon on their turn to fight back and only lose one action putting it back to continue climbing. Someone with Reactive Shield can pull out their shield as a Reaction while they're climbing to get extra defense.
These all influence what people can do in that situation, and give them unique ways to interact as such. It makes for interesting plans and such if you are going to go far up a cliffside as to who can do what and such: who is on defense, how you are going to climb, etc. You start with a basic set of restrictions, and the player's unique abilities attempt to get around the problem in different ways. My immediate thought is something like
COMBAT CLIMBER~! is especially valuable to people who have good reactions, like Champions.
Now if you find that restrictive, that's your taste. I personally like having players have not only the knowledge of what a challenge is likely to look like, but defined unique ways to interact with them. To me, that's a feature, not a bug.
