Beating Mega Satan with The Lost in The Binding of Isaac. I thought it was impossible. But somehow, I did it.

These are the three that stick out most in my mind:

The first time I turned on Xenoblade Chronicles, I had never played a game like it before and had no idea what to expect. I'd only gotten the game because my friends were hyped about it. The game came on, and the title screen appeared, and I sat there for legit a half hour, just listening to the Main Theme play over and over as the screen went from day to night. It was such lovely music and I kept getting chills over and over and knew I was about to play something special before I had even started the game. I had a similar feeling at the end when Beyond The Sky started to play, the only actual 'song' in the game with lyrics and a beautiful singer (Sarah Alainn), because it was just such a great ending to an incredible story and journey, which was at the time, by far, the longest game I'd ever played/completed.

Similarly, in Xenoblade Chronicles X, I was exploring Sylvalum, and it became night, and that absolutely ethereal, magical music started playing, which I always looked forward to. But then one time in particular, instead of glowing silver and teal, everything in the world became bathed in a gorgeous pink and purple aurora. I stood there, in awe, up high, looking over the landscape as the music fit so perfectly with the majesty I was seeing before me.

The Legend of Zelda: Breath of the Wild is full of little bits of Zen. Just the sounds of wind, grass, trees, and animals, and the occasional little piano touches create such an incredibly engrossing and relaxing atmosphere. When combined with the beautiful, stylistic visuals--the lighting effects at dawn and dusk, in particular, when the grass and ground have touches of white and a shiny effect--it takes my breath away, no pun intended. It's truly special, and it happens over and over throughout the game, even if only for a minute or two at a time.

Animal Crossing always feels very zen to me

Tearaway (Vita) - never been so happy to play a game from start to end.

That's how I took it.

I'd say the save rooms of resident evil, or the nexus in demon's souls

Super Mario 64, just enjoying the peaceful garden outside of the castle for hours
Banjo-Kazooie, relaxing in the beautiful and atmospheric hub word
Shenmue 2, enjoying the very peaceful nature of Guilin to recover from heavy fighting
Chrono Cross, listening to the fantastic music while enjoying beautiful and colorful environment s and a deep and dark story
Proteus - the whole experience is based on calm, mystery and relaxation

Same here. There was something magical about it.