What's that one game you can't seem to pass a year without playing, /vr/?

It might be because you find it completely and utterly perfect, and think nothing can compare to it. It's the pinnacle of the genre (or gaming itself) and everything since has paled in comparison.

It might be because the game is far from perfect but, flaws be damned, you still find yourself dragging it out year after year. Partly out of misplaced nostalgia, partly out of a lack of anything else decent to play.

It might be because the modern industry is an unholy shitstorm of money-grabbing, persistent-online bullshit, and that one game helps you remember that gaming wasn't always like that.

What is it, /vr/?