Wario on a friend's gameboy, I think
Close runner up is FF8, not knowing what it even was at the time, but thinking it was mindblowingly photo-realistic.
Or maybe Civ 2 that was installed on a 2nd hand PC we got (until one day I got the bright idea of deleting it, and losing it forever)
When I was a kid, I love war games or any games that has tanks on it. So the first game I played during that time was Battle City. it's a tank game where you gain upgrades by picking up stars. It also has other powerups such as extra life, shield, and instant enemy kill. This is one of the best game I played.