There were lots of great games I remember and lots of interesting moments, but as time passes by it's harder and harder for anything to actually "blow one's mind".
That's why I think what happened to me two years ago is even more mind blowing.
I had been playing single-player stuff (plus some MP arena shooters) for years (I started in C64 era, then moved through PlayStation to finally own a PC). So starting an MMORPG was something new to me, but I would never expect it to have such a profound impact on me.
The game was amazing, especially in three regards: mind blowing graphics, perfect animations and skill-based combat like no other game ever had. That's what initially drew me to it and that was mind-blowing enough, but now I don't think it was the most important thing, because the real "I had no idea games could do that!" experience came a bit later.
Healing and tanking in a beautiful game like this are like no other experience one can have in any video game.
Taking care for other players (or rather: their avatars), for their well being, was something absolutely new to me and gave a satisfaction and feeling that I never experienced before. Taking a boss or a challanging dungeon in a party was also something new, so this adds up to the experience. And in MMO this is not all there is, gameplay and skill are not enough. There's a human interaction, people have their ambitions, motivations and their dramas. Organizing a 10 or 20-person raid is nothing like leading your own 4-character party in classic computer RPGs.
I did a lot of that, especially when I started to play as a tanker. It really is mind blowing how many layers of depth such an experience consists of. Protecting other people, leading a group to a combat with a fierce bosses or into a new unknown dungeon, balancing things out in a guild, sharing loot with others in a fair way, etc.
And tanking is unlike anything else I've ever done in video games or a "real" life. Going first into the danger, taking attention of the monsters upon myself so others can stay in safety. I had to knew all the moves, all the animations of them by heart, often requiring to react in a twitch. If the monster tries to go for someone else, my avatar shouts or magically pulls the monster back. I have to keep an eye on it all the time and on every other character in the party (or at least the key players). It requires lots of knowledge on game mechanics and GREAT awareness on what's going on on the battlefield. Imagine leading 20 people in a battle against other 20 players, making decisions, sending text messages and fighting at the same time yourself. I can't think of anything that engaging, requiring that degree of alertness.
MMOs are different than other games, but taking a role of a tanker or a healer is unlike anything I've ever seen in offline games. Actually protecting or healing others... if one feels what it means. This is the most amazing "I had no idea games could do that!"-like experience I've ever had.
The game was TERA. As they say... The Game of My Life :)