"Emancipation" is quite calming, but when the bell strikes, it invokes a feeling of uncertainty. In later part (about 3:18), it turns into an awesome rousing theme.
"Whiskey Corridor" cannot go by without a mention, especially not with what starts at 2:50.
"Stonehenge Attack". Made doubly terrifying when you hurry to obey the sudden order to drop altitude, not knowing why it was given, and watch as half your allies get blasted out of the sky above you.
Breaking Arrows and Breaking Arrows 2. The tension instilled by the music as you race against the missiles will give you the chills. Especially the last (nuclear) one.
Mobius. Get your plane, listen to the base commander give a Rousing Speech, and go destroy the Megalith.
Ace Combat 5: The Unsung War
"Hrimfaxi". A reprise of the music from the earlier Scinfaxi fight, but with some insane electric guitar thrown in for effect.
"Supercircus". Absolutely perfect for the scene it's pulled on: in the middle of safe territory, the four of you suddenly get Zerg Rushed by 50+ Yuktobanian fighters and what was supposed to be a simple ceremonial flight quickly devolves into a nerve-wracking dogfight for your lives while waiting for reinforcements that turn back and jam the airwaves once halfway there.
"Dead Ahead". Perfect music for hurtling at the speed of sound down a long dark tunnel, and no choice to go forward.
"First Flight". Yuktobania launches a massive raid on your base, but the Four Wings of Sand Island launch for the first time, and utterly curbstomp the Yukes. It's also an orchestral arrangement of "Blockade" from Ace Combat 4. It speaks volumes that a series with so much awesome music thought this song was worth reusing.
"The Unsung War". Latin chanting of the legend of the main characters, with sweeping orchestral music wins it every time.
"Winter Storm". A sort of prologue to "Unsung War", also deserves mention. It is New Year's Eve 2010. Millions of lives hang in the balance; while the war is over, one final mission remains: to stop a massive orbital railgun equipped with a nuclear superweapon, from falling on the capital and causing untold devastation.
"15 Years Ago". Another piano version that you normally hear during Nagase's and Gennette's musings on the Belkan war, but also plays during the final mission if you beat the enemy planes quick enough. This song, along with the ordinarily sappy dialogue, makes those two minutes leading up the SOLG assault practically into a CMOH/Tear Jerker.
"Unsung Heroes". A short, yet still magnificent piece, truly befitting your final victory.
"Glacial Skies". That crescendo though. You can practically feel the icy wind on your face, as there's not a warm instrument to be heard, all shimmering violins, cymbals, and castanets, and even the guitar is razor-thin. Gorgeous.
"Diapason". A rousing, uplifting piece that plays as the player flies in the skies over the capital city of their homeland, pushing the Belkans and liberating the city.
"Glatisant". The beat gives it an ominous feel as you enter your enemy's home country.
"Excalibur", the heavy and medieval-esque movement that plays while trying to launch an attack on the superlaser tower that can cut you from miles away.
"The Inferno". An aptly named soundtrack for one of the most depressing missions in Ace Combat history, that effectively portrays the feeling of absolute dread and terror the inhabitants of Hoffnung must feel at experiencing an all-out obliteration bombing, and the resulting firestorm it spawns. Allied bombers carpet-bombing a civilian city, panicked cries from civilians on the radio, fires raging across all of Hoffnung, it all makes for a gut-wrenching feeling and encapsulates that War Is Hell.
"Contact" is absolutely fantastic. It fits the incredibly frantic dogfight against the ace squadron at B 7 R so well.
"Merlon", or "How to Make Your Guitar Sound Like a Harp."
"Mayhem". Possibly the best non-boss track in the whole series.
"The Stage of Apocalypse". June 6th, 1995. What was supposed to be a support mission for Allied forces in Sudentor becomes one of the most infamous moments in the entire series, as Galm Team is ordered to intercept a flight of Belkan bombers headed for Ustio. Said bombers are loaded with nuclear weapons. If you played Ace Combat 5, you know what happens next.
"The Valley Of Kings" perfectly portrays the feeling that you're going to the enemy base to finish them off once and for all... somehow.
"Avalon". The enemy is preparing to launch nuclear missiles, you have limited time to stop the launch AND you have to fly throught a tunnel to stop it. The first part of the song catches the tension of the moment, but the second part gives a heroic feeling.
"Zero". This is perhaps Keiki Kobayashi's magnum opus. It is incredible. A final battle between two former friends and squadronmates on December 31st. As the snow falls, the fate of the world hangs in the balance and it is up to the player to stop the end of civilization.
Even better, someone made an 11 minutes long, digitally remastered HD-quality version. Here it is.
Ace Combat X: Skies of Deception
Even two "unknown" tracks that don't have a title are good. The first one plays during second part of missions "Ice Bound" and Wild Card", while the second one plays only during the raid on Sachana Air Base in "Blitz" and includes a portion of the game's main theme.
"Malebolge". Fitting for the fight against Pasternak in the CF-44 Nosferatu.
"San Loma Assault" at first seems run of the mill for Ace Combat, until the brass comes in.
If you'd already played AC 4 and 5, you probably knew something bad was going to happen the moment they told you your last mission was a peaceful patrol over Gracemeria. When "City Lights" starts playing, those suspicions are confirmed.
Ace Combat: Joint Assault
"In The Zone". Nothing screams Ace Pilot more than this theme. Possibly one of the most emotive themes ever composed for the series.
Ace Combat: Assault Horizon
"Beyond the Canal", the low-key riff that encourages you to mow down enemies with a gatling gun on a Black Hawk chopper.
"Release", the supremely intense piece played on the final mission, features Ominous Latin Chanting for starters. After an awesome startup with a rising choir, the frantic tone offers a mere couple of soft moments before diving back into the chaos.
The main theme, "Gotta Stay Fly", featured heavily in promotional trailers and making up the overarching melody of many tracks. Unfortunately, it only plays during the ending credits.
"Fighter", the instrumental version of "Gotta Stay Fly", which picks up once Bishop and his wingmen start turning the tide around during the battle on Miami, interceded with a speech from the President of the United States no less!
"Keep Alive". A near-perfect blend of militaristic drums, electric guitar and electronic music samples, creating one of the most amazing songs ever conceived for a 21st century aerial battle.
"Shall Defend". Starts with an almost tragic set of piano keys, but quickly hits you with a rolling thunderhead of tense strings, powerful riffs, and a snare drum that simply will not quit.
"DEJA-VU", the theme of the main enemy of the game. A truly chilling piece of music.
"Naval Warfare" is an unrelenting maelstrom of metal, sounding as though each instrument is going every which way doing its own thing. It's rather fitting for the one level where you get to use the Attacker planes and blow an entire naval fleet.
"Gravity". The Ending Theme with some pretty cheesy, yet absolutely epic lyrics, serving as an extended Badass Boast in honour of Scarface One. note The 3D Cross Rumble soundtrack calls this song "Like a Phoenix Rising," but in the credits for Assault Horizon Legacy this song is titled "Gravity." This is also the name Noel herself used for the song.
"Fighter's Honor". It's been an established tradition for Ace Combat protagonists to get an awesome orchestral song singing their praises for the final battle, and now Scarface One gets his own.
"Locked", Cocoon Squadron's theme; a fast-paced rap number meant to rival Assault Horizon's "Gotta Stay Fly". note The 3D Cross Rumble soundtrack calls this song "Gravity," but in the credits for Assault Horizon Legacy this song is titled "Locked."
"On the Verge", Albireo Squadron's theme; a hard rock/thrash metal tune fit for the rebel's top fighter squadron.
"Stonehenge Remix", played during the Entirety of Mission 4, and has also been used during all the Multiplayer runs against Stonehenge and the Second and Third Multiplayer runs against Moby Dick/Agaion.