This is a point that has been bothering me for a while and hasn't really plagued me until the last few years. It's result is me enjoying the games I play less and less, to the point where I only play them (if at all) 2-3 hours in a day before losing interest. When talking about immersion I mean being wrapped up into a story, being convinced by the mechanics, and glitches/bugs being at a minimum.
It might be the fact I'm very "left-brain" orientated and having a high respect for logic, reasoning, and observation that knowing what is happening behind the pretty colours is what is killing the game for me. When playing an open-world game like, say, Skyrim, it's always in the back of my mind the simplistic AI, the triggers, the fact that there is no AI milling about in the cities because it's not loaded, that behind this wall is nothingness that my character would fall into abyss, AI/Creatures don't spawn until you are in proximity. It is also almost impossible for me to be very immersed in corridor games anymore. I know there is no world outside of where my character is able to go, things like no-clipping in half-life 1 made me realize this at a young age and has spoiled these games entirely for me.
The only thing that keeps me playing a single-player games these days is an interesting story, but even then that is impaired by me being too observational of every other aspect of the game. I'll "grind" through the game just to get the story, though I am left unfulfilled by the experience and would rather have read a book. The best games lately that left any sense of immersion in me would be ArmA2 (where there can be a whole island populated at the expense of CPU power) and flight sims like IL-2 & A-10. And even these games still leave me lusting for more with lacking mechanics. Minecraft would be a great example of a game where I can go just about anywhere I damn well please, but even then there are flaws with this game. Mobs spawning out of nowhere with no previous existence and knowing that outside of where I have explored doesn't actually exist yet.
It's bothering that I don't get much enjoyment from gaming anymore, but maybe in the not-too-distant future I can be proven wrong.