“As you walk down the forest path, you feel the warmth from the sun, and hear the birds singing. You have been walking most of the day passing small ponds, bushes with berries and meadows covered in small flowers. The trail you have been following does seem rarely traversed, as you have encountered no other beings except for a rabbit, that crossed your path. Near evening you a reach a lovely little roadside inn.”
As is obvious the players failed their passive perception roll and did not notice the hidden group of orcs guarding their ill-gotten gains including a treasure map to a nearby dungeon. If you the players had chosen to have a higher passive perception.
This post might be a bit of a rant, but as I am writing these things, and I am in part following the discussions regarding the upcoming Pathfinder 2nd edition and their revisions including new approaches to perception, and it part I have more or less concluded Curse of Strahd and am running the module Ravenloft instead. Comparing the different versions of the Castle Ravenloft text regarding among other things the use of perception and passive perception.
Passive Perception (from D&D 3rd and Pathfinder) is average roll for perception, that the DM can use to see, if the characters notice things even though the players are not asking – and that kind of makes sense, as it is tedious to have the players ask ‘do I notice something now? How about now? Now?’ all the time, and yet their characters might at any moment be passing a secret door in the dungeon or a hidden creature in the wilderness. And asking the players at random moments to roll perception is the same as informing them of something been unseen – you might as well just ask them, if they want to investigate their surroundings.
(When using published adventures the author has determined the DC for the hidden objects, but this does not change the fact, that the passive perception mechanic creates a curious situation, where either the characters do not notice the hidden objects, or it is always the same player noticing things, namely the player who chose that function in the party (and since it is so, perhaps it should be front and center in the character creation: “Choose this class, if you want to be the character who notices hidden things”)?)
Furthermore, passive perception has its another weakness, as the removes a choice from the players and puts it solely in the hands of the GM. Passive perception is a set value, which means that the DM is actually the one to determine, whether or not something is noticed. For instance, a party with passive perception of 13, 14, 15 and 16 is walking down a forest path:
- Hiding DC 13: The orcs are hidden with difficulty 13, and the DM informs the party, that they all notice a group of orcs hidden in the bushes.
- Hiding DC 16: The orcs are hidden with difficulty 16, and the DM informs the player, whose character has passive perception of 16, that her character notices a gang of orcs hiding the bushes.
- Hiding DC 17: The orcs are hidden with difficulty 17, and the DM does not inform the players of the hidden orcs, and the characters continues the trail to the local inn.
The hidden orcs van be replaced with secrets doors or other elements, that are kept of out of sight.
The issue with the Passive Perception mechanic is, that it is solely the DM who decides, whether something hidden is noticed or not – and only the illusion of a simulated setting hides the flaws in this approach, the illusion being that the orcs in hiding and secret doors follows a set of rules that is balanced against the passive perception of the characters, but the same logic allows the DM to include extra well-hidden secret doors or orcs exceptionally skilled in hiding. Again, this leaves it to the DM to decide, if the players find something or not, and removes any choices for the player.
The core design issue behind this is the fact, that in the medium of roleplaying games the players and the characters share the view of the world, and what the characters see, the players can act upon, but the players can also act upon the signals, that the DM sends them (a signal being for instance ‘everybody, roll for perception’), whereas in the other mediums, movies for instance, the view of the setting is not the same for characters as for the audience, and the film maker can reveal for the audience the clues, that the characters missed (and in theater, the actors can play with this, when they speak to the audience about stuff, that their characters missed, but the audience saw).
In other media, the storyteller can reveal to the audience, if the characters missed something, and thus the hidden and unfound object is still a part of the story, whereas in roleplaying games, the hidden and unfound does not enter the shared fiction, and objects outside the shared fiction does not exist (there is no difference between a hidden door never found and a non-existent hidden door).
This is the issue, that hidden objects are struggling with in roleplaying games. The nature of hidden objects is to be found, but how do you find hidden things, if you do not know to search for them?
This is it for now. Next up is a closer look at the nature of hidden things and how to reveal them.
Roles, Dice and Fun 
The critique has a point if one is using roleplaying games as a medium for telling stories, and restricts participants to the viewpoint of their characters.
This is not an issue when not doing at least one of those.
If running the game as a sandbox as a neutral referee (neutral in the sense that one does not make decisions based on whether one wants the players to succeed or fail, or what would make for an exciting story, but rather based on the internal logic of setting), then it is fine for players and their characters to miss things; and, in fact, finding the things is a task at which the players might succeed or fail.