Nei dies, Phantasy Star II. Changes everything after.

Entering Hyrule Field for first time on Ocarina of time back '98 and more recently leaving the dungeon/cave in Oblivion at the start and seeing the open world below with a ruined castle in distance back in '06. Not been blown away since then.

Never played this game (aside from a few minutes in a Dreamcast collection disc) but that moment was such a big deal in gaming magazines of the 90s that I was kinda jealous of Sega gamers.

The second level in the original Halo was pretty mind blowing at the time.

Even though Chrono Trigger is a fairly short rpg, I have to admit how amazing it was when the team found out what the real end goal was and that they'd have to go forwards and backwards through time to accomplish it.