NES. We had Mario/Duck Hunt/Track and Field. That shit was awesome. I definitely played a lot of Mario but I think the first one I really dumped time into was the original Zelda. I remember sitting around for hours playing that. I didn't have the map that came with it for some reason and had to just figure shit out. I remember literally burning every bush I could find to discover secret places.
For PC gaming the one that really got me was Doom 2. Holy shit that game. I'll never forget it lol.