"A red aircraft? I've never seen a paintjob like that before."
Ulrich Olsen[1]

Zone of Endless[2] (abbreviated as Z.O.E.) is an artificial intelligence developed by Gründer Industries. It was installed onto various aircraft and utilized in secret in 1998 during the Usean coup d'état.

Z.O.E. supported advanced maneuvers and was equipped with next-generation technology and aircraft, including the ADF-01 FALKEN. Despite this, Phoenix destroyed most of the Z.O.E. units during the coup d'état.

In 2019, the ADFX-10 UAV that was developed by Gründer Industries, for use of the Free Eruseans, has the emblem of the Zone of Endless project; this prototype served as the basis of the ADF-11 add-on for ADF-11F.



Gründer Industries launched the Zone of Endless project in complete secrecy just after the Belkan War ended in 1995. The Belkan Air Force was crippled after losing so many of its skilled fighter pilots in the war, forcing the country to adopt unmanned technology while training new pilots for the future.[3] Theodor Sander, a Belkan War veteran who joined Gründer's UAV development program, is believed to have contributed to the Zone of Endless project.[4]

Z.O.E.'s purpose as a pilot replacement AI was realized in one key feature: the ability to learn through consecutive battles. Z.O.E. can collect information from battles it participates in, analyze the data, and evolve to overcome its own weaknesses.[3] In practice, early versions of Z.O.E. would retreat when sustaining too much damage,[1][5] while later versions would use more advanced tactics and technology.[6][7][8]

By 1998, Gründer installed the Z.O.E. program onto five separate aircraft: an F-14D Super Tomcat,[1] an F/A-18E Super Hornet,[5] a YF-23 Black Widow II,[6] an F-15 S/MTD,[7] and a newly-developed ADF-01 FALKEN.[8] All of these aircraft were painted in a distinctive crimson finish with no nationality markings, making it appear rogue.[1]

Usean coup d'état

Through unknown circumstances, the five Z.O.E. aircraft arrived on the Usean continent by May 1998. Phoenix engaged the F-14D during the battle of Meriton[1] and the F/A-18E during the battle of Skully Islands;[5] both aircraft retreated after sustaining critical damage. Despite ostensibly supporting the Usean Rebel Forces, the members of the rebellious Cocoon Squadron were unaware of Z.O.E.'s existence.[5]

Phoenix later engaged the Z.O.E. YF-23 while helping Pennant Squadron escape a Rebel ambush. The YF-23 shot down one of the Pennant planes before Phoenix shot down the YF-23 in an extended dogfight, marking his first kill against the AI.[6]

As Scarface Squadron and the Usean Allied Forces began to recapture Saint Ark in September 1998, the Z.O.E. F-15 S/MTD engaged Phoenix in a dogfight. Z.O.E. utilized advanced jamming technology to create false targeting boxes on Phoenix's HUD and radar, but Phoenix shot down the aircraft and continued the mission.[7]

The Z.O.E. ADF-01 attempted to defend Fortress Intolerance during the Rebel Forces's last stand. It featured the most advanced technology, including false targeting boxes as well as backwards-fire capabilities. Phoenix destroyed this final Z.O.E. aircraft as well, opening a path to attack Fortress Intolerance.[8] Z.O.E. has not made an appearance since the ADF-01's destruction, leading to the belief that it no longer exists.


Ace Combat 2

Z.O.E. originally appears as a recurring group of secret aces in Ace Combat 2. The player will receive medals for shooting down each Z.O.E. aircraft. The full list of Z.O.E. aircraft, and their ranks, is as follows:

The Z.O.E. aircraft appear in order, and if the player happens to miss a particular one, it will take the place of the next one. For example, if the player doesn't shoot down the Z.O.E. F-14A in "Sledgehammer", the F-14A will then spawn again in "Seagull" instead of the F/A-18E. Therefore, the ADF-01 will only spawn in "Fighter's Honor" if the player shoots down all of the Z.O.E. aircraft in their first appearance.

In addition, the only way the player can advance to the final two missions, "Last Resort" and "Fighter's Honor", is by shooting down the Z.O.E. aircraft that appears in "Kingpin" regardless of which one it is. If the player fails to shoot down the Z.O.E. aircraft in "Kingpin", they will receive the game's "normal ending".

Ace Combat: Assault Horizon Legacy


Instead of acting as hidden aces (which the game still features), Ace Combat: Assault Horizon Legacy changed the Z.O.E. aircraft to be integral components of the story and required targets for the player to shoot down. This makes it impossible for the player to miss any of them, but they will still earn a Z.O.E.-related medal for completing the campaign.

All five Z.O.E. aircraft are capable of performing advanced maneuvers, even the initial F-14D. Only the F-15 S/MTD and ADF-01 units are capable of radar jamming that disrupts the player's HUD; it creates fake targeting boxes like those seen in "Blind Spot" in Ace Combat 5: The Unsung War. The ADF-01 is also capable of firing missiles and machine guns backwards until it is severely damaged.

The full list of Z.O.E. aircraft in Legacy is as follows:

Extra Missions

Z.O.E. makes two appearances in the game's Extra Missions, which are considered non-canon to the main story.

In "Extra Mission 02", the player must shoot down a Z.O.E. ADF-01 that is flying fast through Seals Bridge Ravine. This ADF-01 uses the game's Color 1 for the aircraft instead of Z.O.E.'s crimson red livery. While its main purpose is to escape the ravine, the ADF-01 will still fire missiles and machine guns backwards towards the player.

In "Extra Mission 04", the player must shoot down the Z.O.E. ADF-01 defending Fortress Intolerance with no changes; it still features the fake targeting boxes and backwards fire. However, after the player makes a U-turn inside the fortress and escapes, four Z.O.E. ADF-01s will be waiting for them. These aircraft do not have the jamming or backwards fire, but they are all equipped with the Tactical Laser System. They are also not the same model as the ADF-01 that appears at the start of the mission or at the start of "Fighter's Honor"; their model more closely resembles the player's ADF-01 in Ace Combat 5: The Unsung War. One of the ADF-01s uses the plane's Color 6, while the other three use the plane's Color 5; if the player has customized Colors 5 or 6, it will be reflected in this mission.

Other games

ACJA Ace of Aces ZOE

Z.O.E.'s "Ace of Aces" appearance in Ace Combat: Joint Assault

Z.O.E.'s crimson red livery has been featured in other Ace Combat games as an unlockable livery, usually for the ADF-01 FALKEN.

Ace Combat Infinity featured the Z.O.E. livery on multiple Special Aircraft:

Infinity also held a "Z.O.E. PROJECT" Online Co-Op Missions Ranking Tournament where players could earn the Z.O.E. livery as skins for the F-15 S/MTD, the F-14D, and for the first time, the F/A-18F Super Hornet and F-22A Raptor (replacing the F/A-18E and YF-22 from Ace Combat 2). The tournament also featured related emblems and nicknames for players to use, including "Evolving Combat AI" and "Self - Propagating".

In addition, Z.O.E. appears as an enemy unit in the bonus missions for Ace Combat X: Skies of Deception ("Operation X") and Ace Combat: Joint Assault ("Operation X" and "Ace of Aces").





Zone of Endless F-35
  • A Japanese trailer for Assault Horizon Legacy features a Z.O.E. F-35C Lightning II during "Green Bird". However, this does not appear in the final version of the game, where the YF-23 replaced the F-35C.[9]
  • The Z.O.E. F-14D in "Midnight Assassin" in Ace Combat: Assault Horizon Legacy features Phoenix's emblem on the nose and vertical stabilizer, likely due to a model reuse.
  • The Z.O.E. F-14D, F/A-18E, YF-23, and F-15 S/MTD in Assault Horizon Legacy appear to use the Color Customization skins painted in red (Color 5, Color 5, Color 5, and Color 6, respectively).


  1. 1.0 1.1 1.2 1.3 1.4 Midnight Assassin, Ace Combat: Assault Horizon Legacy.
  2. Zone of Endless medal, Ace Combat: Assault Horizon Legacy.
  3. 3.0 3.1 Aces At War: A History, page 66.
  4. Ace Combat Zero Assault Records, #124 - Theodor Sander.
  5. 5.0 5.1 5.2 5.3 Seagull, Ace Combat: Assault Horizon Legacy.
  6. 6.0 6.1 6.2 Green Bird, Ace Combat: Assault Horizon Legacy.
  7. 7.0 7.1 7.2 Kingpin, Ace Combat: Assault Horizon Legacy.
  8. 8.0 8.1 8.2 Fighter's Honor, Ace Combat: Assault Horizon Legacy.
  9. エースコンバット 3D クロスランブル 本告PV. YouTube. Uploaded on December 21, 2011.