In your time as a gamer, what game reveals really blew your mind and filled you with excitement? What was it about them that so hyped you?

This one is technically a tech demo, that became a game: 

I feel like every new first-party game revealed during a Nintendo Direct gets me super pumped lol. But if we’re talking the most pumped up? Smash Ultimate easily takes the cake for most pumped up. Then Pikmin 4, SMOdyssey, Mario Wonder, Mario RPG Remake, and TTYD Remake. All blew me away when they were first shown.

Oh yeah! I just remembered: Astro Bot and Spyro: A Realm Beyond. Those two sent me through the ceiling lol.

KARA got me so excited, both as a tech, but mostly as a fan of Omikron: Nomad Souls, I thought this might have to do something with Omikron when that demo was released (they've cancelled the sequel, Nomad Soul:Exodus/Omikron 2: Karma under publisher's pressure to make more games like Fahrenheit back in 00s). 

Unfortunately, it was not meant to be, and while I like Detroit vastly more than any of their post Fahrenheit games, I still find Omikron to be most innovative game that QD ever did (along with being my favourite of theirs) and still hoping that they will resurrect that IP some day.

StarCraft II. Was hyped for years after that teaser dropped.

Final Fantasy Versus XIII. (and FFXIII)

After the masterpieces of FFX, KH2, and FFXII, there was no way SE could fail. I was hyped beyond all measure.

These reveals were an incredible experience:

Another classic one that sent my hype-meter off the charts.
Zelda Twilight Princess

Very much on a personal level, but the reveal a couple of years ago that they were remaking Suikoden I and II got excited like i havent been in a while.

Nothing new lately. But some of the remakes got me pretty hyped like A Links Awakening, Mario RPG, and Paper Mario and the Thousand Year Door.