Thief itself.
The first moment I played it, I thought I wouldn't expect much, but...Despite being a very old game and I played it in 2016, I was amazed by it anyway; the graphics, the sound, the audio system, the music. Just about everything about the game was amazing, even the combat system.
I wasn't much into Stealth games, I actually hated them, but I always wanted to know what is this game, that is nothing more but something simply named "Thief". Why such a mundane simple name? Also, it helps that back in 2011 I saw it on an old now-defunct "gaming" TV channel ran by Italians.
And there is this one moment, when I was playing my first mission, I was already having some "feels" just from the tutorial, but the first mission...The moment I blackjacked that guard, I felt like I made quite an achievement, like a little kid jumping happily 'cos he found something out and his parents are cheering (more like spoiling) him about it.
And then I got down the sewers, I was already mad 'cos I'm one of those neurotic taffers that hate sewers so much, I might as well be Civvie's uncle (because I'm older than him, Gen-X and all that; live young, die young, baby!)
But something got me. You know what it is? The music. The sewers just...Well, it just felt so good being in such a shitty place for once, with that amazing music playing. Eric Brosius is a Legend, he must be a demigod put to Earth and he doesn't know it, not like anybody should know. The sound and music design he makes is out of this world, it made me feel so immersed when I played Thief. Just about ANY sound, ANY song he makes for Thief, it gives me that feeling I don't always get, that feeling of "Relaxation", that feeling that everything is good, for once I really get that one moment to stay away from all my fucking shitty problems and just enjoy "life" by doing something as mundane as playing an obscure old game.
Thief is something, Thief became my second top favourite game (the first one is Neverwinter Nights, the nostalgia that one gives me) and the only thing I regret is...Well, playing it on Summer, when playing it on Winter could have been MUCH better. (Quite a petty regret, I know, don't mind it too much)
But alas, that's how it happens, and I can always replay it anytime, any day, maybe even when I die, because that's how amazing Thief is, it should let you to remember it even in death.