From here:
Observations on GNS Simulationism – Correspondence is about Diligence
I prefer to use a different term to reduce preconceptions and draw attention to what’s pertinent for our purposes. (“Railroading” was conceived as a deconstructive critique of this practice; it’s the name an enemy grants to the phenomenon.) . . .
to put it briefly, I believe that railroading play, despite how common it is, is generally misunderstood to concern itself mostly with the causal “A leads to B” path procession through the GM’s prepared material. This type of railroading theory leads to complex conceptualizations like hub models (alternate roads you allow the players to pick from) and magician’s choice (the players think they’re choosing, but really they’re not) . . .
What I would like to offer as a modest alternative to old-fashioned railroading theory is that the purpose. . . is not to cheat and create an illusion of freedom; it is to exquisitely prepare nuanced literary material for intimate consideration. The strength of the railroading game structure is not in hiding the tracks, but rather in ensuring that those tracks travel through scenes worthy of spending some time in. You’re literally only bothering with the railroad tracks because you don’t want to waste time preparing complex content and then just have the other players skip it; it’s much better to take the track as a given and focus on how to make your content worth the trip.
I’ve written about this in more detail elsewhere, but the key consideration is treating your game prep the same way an adventure video game does: your core strength is being able to prepare carefully, and the freedoms you give to the player are carefully constrained to ensure that you actually get to show off your stuff. It is still interactive, as the player has the primary control over the pace (how quickly you go over your material) and focus (what parts of your material are particularly observed) of play, even as the GM by definition holds primary content authority. The GM decides what play will be about, but the other players decide how they investigate that aboutness. . . .
It is extremely important that the introduced matter is good stuff, creatively relevant to the participants. Tracy Hickman understood this in his magnum opus Dragonlance, pushing the AD&D content delivery chassis to its extreme ends and beyond in an effort to deliver a true high fantasy epic via a game structurally very poorly suited for the purpose; Hickman understood that if there was to be a measure of grace to the project, it would be in the fact that the GM would . . . be delivering actually legit fantasy literature. (Not discussing the Dragonlance novels here, note, but the adventure modules.)
You never, ever want to be in a position to deliver . . . trivial material. Respect yourself, respect your friends, and . . . bring something you actually want to tell the other players about. Something that you can describe to them, and then let them ask questions, and then answer those questions gladly, confident that you’re engaging in an intelligent, meaningful activity. If you can’t convince yourself about your material being interesting, don’t expect others to care, either.
Upthread I've posted about CoC scenarios that I have enjoyed that have exactly this character. And
@AbdulAlhazred has often posted about his friend Mike who was an awesome GM along these lines. Eero is talking about, and trying to analyse, this very popular approach to RPGing.