video game that takes place 15 years before the events of Ace Combat 5: The Unsung War. The game revolves around the rising of tensions between Belka and the combined forces of Osea, Yuktobania, Ustio and Sapin. Several characters from Ace Combat 5 make an appearance in Ace Combat Zero, but they appear in tertiary roles. The player plays as a mercenary, "Cipher", hired by the country of Ustio, which was invaded in an attack from Belka. Many elements from Ace Combat 04 and 5 are in this game like "Pops" and the Superweapons. The game features primarily older versions of fighter aircraft seen in its predecessor game, such as F-15, F/A-18 and several second generation aircraft like the Saab Draken.
The player will go up against enemy ace squadrons that feature enhanced weaponry and combat prowess. Players who destroy everything without regard to hostility will receive the "Mercenary" rank, players who instead spare neutral targets will receive the "Knight" rank and those that strike a balance between the two will earn the "Soldier" rank. These ranks will affect which enemy ace squadrons a player will face throughout the campaign. A split-screen versus mode is included with the game, but no online feature exists.
Unlockables
ADF-01 Falken With AC5 save file in the same memory card, to get a Falken for purchase, just beat the game in all 3 Ace Styles in any difficulty. It's a lot easier than the normal way (obtain 3 Supreme Medals).
Note that the save file must have the same language (AC5 JP save file only works for AC Zero JP)
Falken - Beat the game in all 3 ace styles with AC5 save data or obtain 3 Supreme Medals
Decorated Hangar Obtain S ranks in all 55 missions on ace difficulty to unlock a new hangar, decorated with Ustio and Galm team flags.
Expert Mode Expert Difficulty - Beat Hard Difficulty
Extra Paint Schemes Complete campaign mode on any difficulty as a Knight, Soldier and Mercenary to unlock that respective paint scheme
Free Mission Mode In this mode, you may play any previously completed missions. You will still receive credits and can improve your rank for the mission, but your Ace Style will not change.
Free Mission Mode - Clear Campaign Mode once
The Gauntlet Defeat all major (mission-required) enemy Ace Squadrons.
Unlock Scene Viewer and Music Player Clear the single player Campaign once on any difficulty and with any Ace Style to unlock the Scene Viewer and Music Player in the Ace Style>Gallery.
Unlock the F-22A ,X-02 and ADF-01 Complete the game once with any difficulty to unlock the F-22A. Complete the game twice with any difficulty but with a different ace style to unlock the X-02. Obtain all supreme ace medals to unlock the ADF-01. You will still need to buy those planes after being unlocked.
Unlock X-02 (Easy Way) Normally, you have to beat the game twice to unlock this plane but if you have Ace Combat 4 data, it is much easier.
Unlock X-02 after finishing 1st mission - Have Ace Combat 4 data on your memory card.
Unlockable combat fighter In mission 3 shoot down the Rot squadron.
Unlockable Plane Beat campaign mode on any difficulty with all three different ace styles.
Unlocking Medals Unlocking the Supreme Aces and regular Ace medals are different. To unlock the standard ace medal, you must clear the game with the arrow in that ace zone. To unlock the Supreme Ace medal, you must be as far into the zone as possible
Broken Sword - Clear Mission 9
Bronze Ace - Destroy 200 enemies
Bronze Wing - Get an "S" rank on every mission with all three Ace Styles on Normal difficulty
Deliverance Bell - Clear Mission 6
Expert Marksman - Destroy 50 enemy planes using only guns
Gold Ace - Destroy 1000 enemies
Gold Wing - Get an "S" rank on every mission with all three Ace Styles on Expert difficulty
Guardian - Clear Mission 5
Knight Ace - Clear game as Knight
Marksman - Destroy 5 enemy aircraft with only guns
Mercaenary Ace - Clear game as Mercenary
Ragnarok - Clear Mission 15 with an "S" rank
Sharpshooter - Destroy 15 enemy aircraft with only guns
Silver Ace - Destroy 500 enemies
Silver Wing - Get an "S" rank on every mission with all three Ace Styles on Hard difficulty
Soldier Ace - Clear game as Soldier
Supreme Knight - Clear game with the arrow at the right end of the Style Meter
Supreme Mercenary - Clear game with the arrow at the far left end of the Style Meter
Supreme Soldier - Clear game with arrow in the center of the Style Meter (above the D in Soldier)
The Gold of Annwn - Clear Mission 17 with all targets destroyed.
One of the best intro cutscenes of the series is available here: