Role-Playing Game Theory
If you are new to Role-Playing Game Theory you might want to read over this great article I found on Exploring Believability first (though I do get into specific examples fairly quickly).
As a GM with intense Gamist roots (console RPGs and AD&D 2nd Ed.) I found out quickly that Simulationism was a dirty word in role-playing circles. On one hand it conjured images of unnecessarily complex rules systems, page after page of charts full of minutia, and on the other, LARPing. I was raised to believe, from reading AD&D manuals and talking to other GMs, that Simulationism is neither an achievable or desirable goal. And that fact was the reason that Gamist systems relied on abstractions.
On My Slow Exodus from Gamism
During an early AD&D game session, while describing the room that the PCs had entered I was asked for some additional description focused on a specific object which the game materials barely mentioned. I complied, feebly, as I had no experience running 'off-the-cuff'. Luckily, my players enjoyed my improvisational description and asked for them more and more often, and I got better at giving them.
The ability to do this seamlessly became very important to me because I didn't want my players avoiding role-playing by "gaming" me (asking about each possibly significant item in the room and waiting for my poker face to crack) to find clues.
This eventually led me to an off-the-cuff game running style. Before each session I prepared a simple overview of what (or, more often where) the PCs planned to adventure (a hastily scribbled map and some notes about the creatures there). Running AD&D this way, a game which required quite a bit of GM preparation, was difficult, but I managed it fairly well. I found that I could 'roll with the punches' my players handed out far better this way.
I'd say, at this point, that 'railroading' became a thing of the past, but it's not true. It never was 'a thing' because my players came from the same extremely Gamist position I did. They played the same linear console RPGs that I did, and never expected to be able to choose the direction their characters went, at least not in any broad sense.
Once my players got a taste of 'true adventure' there was no way I was getting the lid back on that ol' box of Pandora's. My players wanted this kind of open-world adventure everywhere, but with that came a desire for a type of cinematic moments that AD&D's game system had no way to approximate.
"You want chunks of wood flying from your shields, and your armor taking damage from deflected attacks?" Yeah, AD&D can do that with a little GM intervention. The game gets a little more Simulationist, but it's okay. A little house rule here, a little patch of the AC system, and done.
"You want graphic descriptions of wounds?" I think that can be done. I make a dozen critical hit tables and house rule the shit out of Hit Points. But, we try it out and it doesn't work. The tables look good, and there are a lot of interesting variations, but it still feels broken.
AD&D kept telling us, each time we modded the game to make it more cinematic, that Simulationism was not achievable. No amount of house rules would turn AD&D into the cinematic high-fantasy game we wanted to play.
My players were sad, but I saw a greater truth. Every edition of every game has its own unique spirit created at the intersection of the rules system and the game setting. To turn AD&D into the cinematic game we wanted to play would have been tantamount to ripping out its soul. So, the problem wasn't AD&D, it was that we were trying to play a Simulationist game using Gamist rules.
But, we didn't even know if it was possible to make a Simulationist game. In fact, we didn't know any game systems aside from AD&D. So, we went to the opposite end of the spectrum. If AD&D wasn't the way to do it then maybe we didn't need dice, or rule-books, or character sheets.
This, of course, didn't work. We were back to Cowboys and Indians.
I played a bit of Vampire: the Masquerade and Shadowrun in high school under different Game Masters. Both experiences were negative and turned me off to systems other than AD&D (the GMs were strictly authoritarian Gamists trying to run what I later learned were Narrativist / Simulationist settings). For years we avoided them, but in our quest to find a Simulationist game system we ended up giving Star Wars d6, World of Darkness, and Shadowrun a shot (I won't mention the hundreds of other games we tried during our "experimental phase").
The answer came to us when we realized that we had the wrong definition of Simulationism. It didn't mean 'to simulate reality using dice'. We weren't interested in simulating reality at all. Shadowrun made an excellent stepping stool to get away from Gamism, and World of Darkness allowed us to take a full, unhindered step into Simulationism.