Question: How to allow failure but maintain verisimilitude?

So, my first real blog post, but I'll restrict the self-indulgence to this sentence.  The point:  relatively recently I committed myself to making a game, having never done anything like that before but having an idea for a game that I wanted to explore and also to give myself the challenge of completing an ambitious project by myself, which I have often struggled with in the past.  (It will almost certainly be a Source Mod, for the record.)  I'm very much still in the thinking stage rather than building anything in a level editor anytime soon, but I've run across an issue which is fairly hard to reconcile and yet fairly central to what the game will be like.  I'm genuinely interested in what suggestions people have to get around the issue.
The actual point/issue this time (in condensed form):  There has to be fail states in games where right decisions need to be made in order to progress, but being able to retry after having failed strains the sense of verisimilitude the player might feel with the game and is compounded by any subsequent repetition of game elements that the player then experiences.   That sentence was considered carefully but it may still have flaws so feel free to point out any amendments to it if you are able to argue them clearly.   When saying ‘verisimilitude’ I’m meaning a gaming experience that shares enough similarities to reality such that the player instinctively starts to interact with the world as they would in real life and has expectations of the world that they have of the real one (I think the same probably holds true even if the player is consciously role-playing).   That above phrase doesn’t apply to the majority of games since many don’t try to achieve that (fair enough) and many revel in their ‘gameyness’ – personally I’m particularly interested in games that try to create that verisimilitude since there are things that can only be explored and encountered when that is the case.   You may think this is weird because as gamers we’re used to dying and then just trying again so don’t see what the big deal is, but I’m fairly convinced this is because we’re often not playing with a real sense of verisimilitude with the game world and this is precisely because that’s so easy to lose and so hard to maintain.

For the game I’m thinking of creating, this issue is made more complex because at the beginning of the process, when I was deriving the core elements of the game that should be upheld during the creative process, I decided that it was key that the player felt like they were thinking for themselves and applying their own intelligence to the problems they’ll face in the game.   This is important and awkward because the problem created by fail states (dying) could simply be reduced by making the game have no real challenge or by doing a lot of hand-holding and guiding of the players - exactly what I don’t want to do.

So what suggestions do people have for a good solution?   The obvious way would be to try to cleverly reduce the number of places in which a player could die, but maybe someone has ideas that work completely differently.   Here are a few of my ideas so far:   if a player fails a challenge early on, the like of which could lead to failure/death later in the game, they do not lose if they fail but are instead taught (in some way that makes sense within the world) what they should have done differently.   Hopefully this will start to get the player thinking successfully for themselves to the point where less hand-holding needs to be done.   To generally reduce the number of places in the game where the player could fail, but to have negative lasting consequences for other failures that do not lead to a complete game over.   To include some randomness in the events that occur (at least in their order) so that if a player fails because of one event, they are not confronted with the exact same one again immediately which keeps the game fresh and I think gives a greater chance of keeping the verisimilitude of the gaming experience.   If the player dies/ fails try, as much as is possible, to have the last save point at an occasion and location which makes sense within the fiction of the story and generally feels natural to the player.   To have an in-game help system (again, making sense within the world) that offers help if it looks like the player is struggling to complete the necessary tasks, thereby reducing the chance of failure – need to do this carefully to make sure the player feels like they solve any challenges themselves.

I’ll leave it there.   Hope that made sense since I’m aware this is all fairly abstract – I’m not going to give away the whole game idea here.   I’ll add a few details that could be useful:   this isn’t going to be a big gaming experience but maybe just around 30 minutes and will all take place within one confined space (no it’s not an escape-the-room game in case that’s what you were thinking).   So yeah, leave any ideas below if they spring to mind or poke me if anything I said didn’t make sense or if I need to explain myself in more detail.