Whether you started with a 2600 and a joystick in your hand, an N64 with a blistered palm or building your first PC in your teens, what is that one video game you've played at some point that to this day sits at the top of your list.
Dishonored, I absolutely adore that game, and it still looks so good because of the art direction they took with it. Funny enough, it was the same art director as Half Life 2
The Outer Wilds. IMO, non-violence-based gameplay design is an underexplored space, especially in 3-D games. The Outer Wilds manages to feel like a fully-fledged game, rather than a traditional walking simulator, using exploration as it's core gameplay loop.
Further, it's main progression system is you, the out-of-game player, learning about the world. There's no abilities you gain or keys you have to find. You unlock new areas, not as a programmed game mechanic, but as a function of reasoning about what you've discovered and gaining insight into how the game world works. Any playthrough could be beaten in about 15 minutes -- there's nothing physically blocking you from triggering the end of the game -- but it takes you 15 hours or so of flying around the solar system to accrue the necessary insight to get there.
Final Fantasy 6 for me. The bad (mad) guy TRULY winning was just the coolest as a kid. It definitely tore apart my expectations for what a good game was ever since.