FFXIII is the most nostalgia-rich and satisfying game I play and it's not even close.
Even though it's not a game I played until my 30s, or played the most, FFXIII hits my nostalgia and comfy gaming buttons the hardest. The music, art design including color palette, and graphics in general bring back good memories of 15 years ago when I finally got my first HD gaming setup, playing on Xbox 360. FF12 is my favorite FF game, but FF13 is special to me.
Even aside from nostalgia, from the get-go this game always feels so comforting, I make a nice coffee, lay back with a good meal in me and lose myself for the day.
It's a game I can pull out every year. Every song is catchy and sticks to my brain like peanut butter. Every area is a joy to look at. Every button push makes a sound that gives me a little burst of satisfaction.