Breath of the Wild: stepping out of the cave in the begining, seeing that vast world in front of Link waiting to be explored

The Switch was the first console I had since the PS2, and the PC "gaming" I did in the meantime was mostly retro games on emulators or a bit of Stardew Valley, so the contrast to that was HUGE.

Another one was re-playing Ragnarok Online months after quitting (and giving away all equipment and deleting all characters) with a friend. We were barely second job class (he was Hunter, I was Priest) and rudimentarily equipped enough to beat Abyss Knights, so we went leveling in the area where those sometimes spawn. AND ONE OF THEM DROPPED A CARD! Cards are extremely rare (allegedly 0.01% drop chance) and monster-specific, and the Abyss Knight card is extremely valuable. So from one second to the next, we practically went from piss poor to rich AF.

Another extremely lucky moment was in Diablo 2: a regular cow in the Cow Level dropped a (perfect!) Windforce, at the time one of the best unique items in the game. I don't remember exactly but IIRC from some online calculator the chances for this drop were under one in a million (I wasn't even wearing anything with lots of MF%)