So, this is not strictly true. In fact, there are entire genres built around accounting for exactly that. To be sure, game design based on player immersion is much more artistic and subjective than game design based on systems, but it is definitely not out of reach.

You can give some people the most immersive possible experience and they won't get drawn in even the tiniest bit. Some other people could get deeply immersed in solitaire. I can plan to immerse as many people as possible, but I can't acvount for them. There will always be people for whom it holds no meaning, it's just a toybox to roll around in. (That group will NOT like this game.)

Player immersion is not something that the player chooses to engage in. They have to set the conditions for it, but you as the developer have to actually create it, if that's the route you want to take. And keep in mind, it may not be the best option. Immersion and entertainment are orthogonal attributes of game design. Particularly in a sandbox or procedural game, it could be incredibly difficult to construct an immersive experience, and even if you did it might not be as entertaining as a more rule-driven experience.

"Immersive" and "rule-driven" and not contradictory terms. In fact, consistency is a vital part of immersion. Ignoring you own world's rules is the fastest way to break immersion. The rules in this game are gospel, and any rules for player dissociation must be consistent, or they'll break immersion too.

I think we're sort of talking past each other at this point.

This happens a lot with me. And it irritates me to no end.

In any case, I love survival games and psychology so I look forward to playing whatever you come up with. Best of luck!

I also love survival games, and I would say I enjoy psychology at least in theory, but the word brings my mind to the ridiculous, confirmation-bias ridden, anti-scientific and worse than useless way it is researched, and then brings up the word "psychologist" and the ridiculous, confirmation-bias ridden, corrupt pill-pushing sellouts that use the it like "Modern Warfare" type games use the word "realistic", which is the kind of use with "ab-" attached to the front of it, so I guess I really can't say that. So I guess I'll just say I enjoy survival games and the human mind.

Killing zombies is a gaming trope, if players saw hordes of real or fake looking zombies and were given a shotgun they'd attack them all.

I can't really argue with you on the player's behaviour, but I can tell you that's a bad idea. Zombies present in this setting work differently, in a way more practical for the setting that came out as something between "voodoo zombie", "fantasy zombie" and "wild animal". Shooting at these bipedal animals is picking a fight you don't need to have. At least, assuming we mean wild zombie humans, because there are people who use zombies for labour or warfare, and then there are zombie dogs, and either way those tend to be more aggressive.

The trope is not much different from a learned response. A sane or fearful person runs away from zombies, but someone who's gained knowledge will behave differently.

In this case, somebody who has gained knowledge (and feels like putting out the effort) will look for the zombies' alphas, kill them (or just kick the crap out of them), put down any resistance, and then take control of the pack. And now they own a pack of zombies.

For this exact same response, you need to reward the player for going to the danger, doing nothing when they run away is sufficient to make a smart player change their mind. Get nothing for doing nothing is a common assumption.

I think you are missing something. A lot of somethings, if you think avoiding a fight is doing nothing. This game rewards accomplishing your ends while avoiding a fight more than by starting one, though they both have their benefits. And it has to, because accomplishing your means without fighting is more difficult, takes longer and requires more effort.

Ok, you did reveal more info about the game here than I originally had available.

I'll have to think about this a little while.

My original response was just hinting at how one would think before the discovery of what you told me . Indeed a new player misses things by making false associations, or not trying enough experimentation. This is more about how you can't predict every move a player will make from start to the finish of one game session, but you can set up the environment.

If it'll help, I'm talking about using things like stealth. Sneaking into an encampment to steal resources is generally better than attacking it, especially in the long run, but attacking it is faster, simpler and rather a lot easier. If the encampment is of creatures capable of speech, such humans or troglodytes (which are technically also human) you might also try talking to them, using persuasion or bartering to get what you need. If you pull it off, these get you those resources without being injured, killing anyone (a major factor in your dissociation) or creating a power vacuum. (An important concept, because the random encounter system is tied to existing encampments. Clearing out an encampment removes its associated encounter from the table, making all the other possibilities more likely to come up.)

That was just an example. He said it was a survival game, and I wasn't sure whether it was a zombie-survival or wilderness survival or something else.

Post-apocalyptic, kinda. Hard to really put the setting into a single term, it's rather complicated and there is 70 years of alternate history I'd need to cover first. I can say that most of European civilization has collapsed as the result of massive nuclear bombardment (in the '90s, mostly from the US) and the game takes place while the EU is trying to recover, what's left of the US is being forced the clean up its mess, and Russia is doing most of the US's job but also trying to annex the region. The game itself takes place in the Black Forest, a wooded mountainous region in south-western Germany, during the winter of 2015.

This region isn't real important to all of that, though. The player's main threats are the environment, various regions where the fallout has settled that haven't been cleaned up, the bizarre wild-life and their own slipping sanity.

My point was more, if the game is to have long-term gameplay, then you can't use an "illusion" that the player knows is an illusion, or it won't work well.
If the game is filled with zombies but no ghosts, and the player sees a ghost, the player knows (by already being experienced with the game) that ghost = illusion, and he just ignores the ghost because it can't harm him. The illusion (on the player) doesn't exist, because you might as well just make floating text say "ILLUSION" instead of a ghost.

That's wrong for a couple reasons.

1. You are assuming that ghosts are obvious, and they're not. All the ghosts present look like regular people when they're initially seen, and their behavioural differences are subtle. As there are regular NPCs in the game, and the only initial hint is that it's an NPC they've seen before (and there aren't any generic NPCs in the game), this makes it extremely likely they'll have no idea if the person they're seeing is a real person or not.
2. You keep assuming that an illusion can't affect you. That is not true. Their presence consistently has an impact on your character. Just because they can't inflict real damage doesn't mean that you can just ignore them. I already said this once.

But if the game is already filled with real zombies, then having an identical zombie appear as an illusion would actually trick the player, and the illusion would be effective. Same with having a tree appear behind you: Because there are other trees in the game, the player can't file away in his mind "tree = illusion", because 90% of the trees he encounters aren't illusions.

This kind of thing is done a lot. For instance, the densest pockets of radiation in the game give off a faint blue glow, and if you have a geiger counter (not hard to find) you'll be able to detect radiation from its ticking. Hallucinations can make you see a blue glow where there isn't one and hear ticking when your geiger counter isn't ticking. Most of your auditory hallucinations seem a lot like real things, as do visual ones.

But, if the game isn't a campaign game and is designed for replayability or long-term playing, if a ghost only appears during illusions, then 'ghosts = illusion', and can be dismissed by the player without changing the gameplay or affecting the player's actions. It might as well not exist (unless it is only ever used once, such as in a campaign). A ghost-illusion appearing in a game without ghost-enemies is as pointless as illusions changing the texture of a wall from a grey stone texture to a brown stone texture... after being encountered once, it can be ignored by the player, mentally filtered out, and no player-behavior or gameplay is affected. It adds nothing to the experience after the first encounter - and players are very very good at automatically filtering from their conscious data that they don't care about; like internet banner ads, 'seeing' them but not 'noticing' them until they choose to.

This game doesn't have a story or a campaign. Now we can stop talking about if it did.

Yes - which is why illusions, if they are to have long-term gameplay effects, must be able to be mistaken for the real thing in the game, which means the real thing must also be in the game (and be vastly more common than the illusion version). Or you just gain knowledge that, hey, ghosts can be ignored.

If the game doesn't have zombies, then a zombie-illusion is just as bad a choice as a ghost-illusion.
If the game already has ghosts-as-real-enemies, then a ghost-illusion is a good choice - because then it can actually be mistaken for the real enemy.

This wasn't really a good argument to begin with for a lot of reasons. One being that the hallucinations are not a constant thing and most players will have doubts until they happen multiple times. Another is that hallucinations seem very real, even when attacking you. This isn't something I made up, either. Schizophrenics, for instance, experience hallucinations with all of their senses, and can hallucinate pain and injury even when it doesn't exist. My ex, for instance, once heard a gunshot behind her (a real gunshot, but that's not the point) and suffered a flashback. She seriously believed she had been shot again when she very clearly hadn't, complete with shortness of breath, pain and bleeding. It took some convincing to get her to realize it wasn't real, and the pain still didn't go away for over an hour. Your character isn't necessarily a schizophrenic, but their hallucinations feel extremely real as well. Ignoring hallucinations, both in-game and in real life, is a BAD IDEA.

But it'd be nice to add some very very subtle hint that it is an illusion, so rewarding players who learn to be extra observant in your game. Like zombies who don't cast shadows must be an illusion, or zombies that are only a tiny smidgen bit transparent (97% opaque instead of 100% opaque).

There's one hint. Your perception highlights objects and gives them outlines, with your perception score determining the strength and range of this effect. Imaginary objects are not highlighted and are not given outlines. If a person you're looking at doesn't have an outline, and isn't a bit brighter than their surroundings would suggest, they are a figment of your imagination.

That's a very good point.

Makes me almost think of will-o-wisps, which would make for good illusions. Some game-real will-o-wisps could lead you to treasures, but an illusion-wisp could lead you into an ambush or just get you lost in the woods and then disappear (and up your hallucinations high enough so you get really disoriented).

I'm not putting in wisps. There's already plenty of deceitful illusions.