Ace Combat 04: Shattered Skies (PlayStation 2 - 2001)
A world in conflict. An enemy to be reckoned with. An ace pilot ready to take command.

Ace 04 is the most successful and highest rated game in the series. While it's easy to think the game's fortunate release period helped it out (at a time when the PS2 was still getting off the ground), that wouldn't change how flat-out amazing the entire production was. The previous three games had performed well, with visuals and gameplay to match, but 04 made a truly tangible leap in terms of graphics and presentation. Terrain, even from high altitude, looked convincing, not just an assemblage of solid-color polygons shoved together. Real-world sounds from the actual jets made it into the game too, offering a previously unattainable level of realism (aside from the fact the planes could carry 50 missiles or so).

The storyline returned to the world introduced in Ace 2, taking players back to Usea just after a massive asteroid hit the continent. A massive assortment of railguns has since been built to blast asteroids out of the sky before they enter the atmosphere - its name is Stonehenge, and it's already been taken over by the Eruseans. As a silent member of the Mobius Squadron, it's up to you and your team to beat back the Eruseans, reclaim Stonehenge and get your ravaged country back on its feet.

As impressive as the revamped aesthetics were, the game's storytelling improved just as much. In between each mission you're treated to flashback, postwar letters that chronicle an orphaned boy's life in an occupied town. These letters, all addressed to you, tell of an enemy pilot named Yellow 13, who the boy befriended while living in the area. Eventually, it's revealed that Yellow 13 is responsible for the boy's parents' death. This after-the-fact, soothingly calm method of delivery made the jet action seem all the more intense and managed to add depth and character to a game where the main stars are supersonic jets, not people.

Defining moment
Off the top of our head, we'd have to say all of it. The sights, the sounds, everything was state of the art when the game launched. It was one of the first PS2 games that made everyone go "are those screens for real?" The cutscenes were just icing on the cake, giving us a reason to care about this war without getting heavy handed or melodramatic. But, if you want to press for an in-game moment that totally kicked ass, how about the final run at Megalith? Death Star trench running at its finest.