Ace Combat is one of my all time favorite series. Enough to say that I got myself a PS2 only to play that game, because emulators, despite all their advantages, can’t deal with its analog controls properly.
But I also have to admit that Ace Combat 4, Ace Combat 5 and Zero are kind of the same game. You fly the same jets, you have just a couple of weapons, and you mostly just shoot missiles at everything.
What varries is how the story is presented. Ace Combat 4 uses anime stills. And the story is not about you, but about your adversary, called Yellow 13. He is viewed through the eyes of a boy, whom he orphaned by accident. The boy works in a pub where the occupier pilots gather. Bartender and his dauther are part of the Resistance, though, and wait for the occupation to end. Despite the dauther being secretly in love with Yellow 13. It is a nice way to tell a story. Contrast this with “in your face” storytelling of Assault Horizon.
One problem I have with the game, though, is that a lot of mission are “earn X points before time ends”. Which means that instead of engaging with mission objectives, you are just caught up in an endless foxfight. That also means you have to resupply once or even twice through the mission.
There are some signature missions, though. When I saw a ravine in Mission 7, I imediattely knew where this was going. And right on queue, and orbital cannon starts to fire at you, and the only way to dodge it is of course to navigate through the ravine.