After completing Mission 30, the game doesn't actually end. Right before Tewy died in Mission 29, her mind got sublimated into a nearby drone and escaped, possibly an early, proof-of-concept, localized version of the Electrosphere, who knows. The drone secretly escapes far, high, and fast eastward.
...
The screen turns black, and it shows a title card:
MISSION 31
| REX |
...
This is where XO Piker stages an emergency meeting and briefing. She had been in contact with Rosie Falcinelli and La Chanteuse, and they found something disturbing. Turns out the war is not yet over. At least with Enso Order.
During their investigation and thanks to their world-wide intelligence network, they discovered that Enso Order still had one secret facility existing. Where would that be? An underground facility in mainland Sotoa, where their old capital used to be.
How did they come about this information? Back shortly after the Tonitrus Spears started destroying Enso Order facilities around the world, they managed to procure recordings and connections of several few disgruntled former Enso Order employees that were working in the old capital. These particular employees were native Sotoans, and they were realizing that all the war effort was absolute bullshit and fearing that they could be disposed of like the other locations, so they discretely defected and escaped with some information.
Back during Sotoa's rapid industrialization which decimated their agriculture, Enso Order struck a deal with Sotoa. Since Enso Order specialized in technological infrastructure, they helped Sotoa build megafloats including their eventual new capital, Ibirsh, and in exchange, Sotoa permitted them to build facilities in their old capital right on the mainland. Enso took heavy advantage of this and secretly built an underground facility and started extracting natural resources in the surrounding lands, in which they helped build the Sotoa war effort and war machines which led to the invasion of Usea, and also led to the research of the X-40 project.
La Chanteuse and Rosie then explain that since the Tonitrus Spears are no more, Enso Order had to do with a different method of physically destroying their final facility, by using UAV drone attacks to destroy the underground facility from within.
These defectors provided a full floorplan/map schematic of the facility. XO Piker brings up these plans and whaddya know, there are several large tunnels running beneath the capital, just large enough for a jet to fly through. The plan is for Joker Flight to prevent the destruction of this facility, as it is the last true surviving evidence of Enso Order's diabolical schemes, and enemy's plan is to send their UAV drones to fly in and hit critical infrastructure to bring it down. These UAVs are produced and launched out of separate facilities near the main underground facility. Currently, some of the defectors of Enso Order have barricaded themselves to prevent the tunnels from opening, however Enso Order is doing everything they can to do so and destroy as much of their evidence as possible.
But that was not the true kicker. The real meat is what was flying in one those drones. In an intercepted transmission, you could hear Tewy's voice, even though she's supposed to be dead. She says her mind is not her own, she can't seem to "move", and Enso did something to her, her only motive is to keep flying and fighting.
That's when Cope chimes in your head.
Cope: "Holy shit. Is that... what happened to me? Being in your head?"
Because of the absolute urgency of this mission, Joker Flight once again has to sortie as soon as possible, as not only are they the only available flight, but the best flight possible on the FCU side. The other squadrons that took part in the defense of Cima Island either had already flew back to their respective bases or were grounded to due damage/lack of fuel. Both the Endurance and Cima Island base only have enough fuel and munitions for this sortie, as they can't afford to waste time getting resupplies.
This meant Dealer had to stay behind as his AWACS plane, an E-2D, was not fast enough to catch up, and precious fuel had to be rationed for Joker Flight's final sortie. Dealer could still relay information in the Endurance's communications array, but at a limited capability compared to his AWACS plane.
Joker Flight sorties one last time, with D.D. watching and speaking to his smartphone live feed.
D.D.: << There they are everyone. The Wings of Theve... no, the Hand of Hope, taking flight one last time. >>
...
Mission 31 starts with a small cinematic. And for the AC04 fans, "Rex Tremendae" plays. Pretty thematic if you ask me.
Rex,
Rex tremendae majestatis,
qui salvandos salvas gratis,
salva me, fons pietatis.
The sky is overcast, with a big break in the clouds over the city. Sunrays shine down throughout. It almost looks biblical with the lighting. The scene shows UAV drones trying to destroy the city around the facility, preventing any chance of anyone trying to investigate Enso Order once the underground facility has totally been destroyed. War crimes everywhere, civilians begging to be saved waiting for rescue. They constantly fly over the main tunnel entrance of the underground facility, waiting for it to be open, as the defectors hold out as long as they can. Because of the fact that the entire Sotoan airforce has been annihilated in Mission 28, the city has no way of defending itself to shoot down the drones.
The situation looks grim and hopeless.
And that's where Coster chimes in.
Coster: << Come on guys.. Baxter would've told me to pump up some tunes already, so here you go. Rex, just do what you always do. >>
Coster then plays a recording of brand new song that Purple Magic never finished. Ever since the 2nd Retaking of Theve mission, it was always on his mind to finish their final song, and this is the moment where it plays. The song carries a subtle punch of hope and to carry on with your duties to the end.
...
Joker Flight shoots down as many drones, preventing them from bring about more destruction to the city, but they just keep coming, endlessly. With each wave and iteration, the drones seem to be... improving?! It turns out that dead-copy Tewy had uploaded some impartial copies of itself into the later waves of drones, making them partial dead-copys of Tewy as well. The main dead-copy of Tewy is flying about above in a new X-40 Nightmare, harassing Joker Flight, and trying to prevent them from destroying the drone deployment facility areas. Joker Flight pulls back a bit to regroup, trying to think of another strategy. The main dead-copy Tewy doesn't give chase, only to guard the facility as close as possible.
Joker Flight was practically fighting on fumes, with their munitions dwindling down.
Kate: << What can we do? We can only do so much. And I don't want to lose another flight mate ever again. >>
Tasha: << I promised myself I would never pull this trigger, but I keep thinking of what if a missile I fire hits a civvy down below? >>
Coster: << We can only do our best, right Rex? >>
But then, Dealer from the Endurance chimes in.
Dealer: << Joker Flight, several contacts detected! 17 bogeys. Bearing 022. Speed 900 km/h. Altitudes at 4, 6, and 8 thousand meters. But... they're not transmitting Sotoan signals... >>
Cope: << Wait... those are numbers I mentioned before, what does this mean? >>
This is where Tasha's dad came in super clutch: In advance, he had contacted his wife to see if the Yuktobanian Airforce can lend aid, and she readily agreed as she and several Yuktobanian Joint Chiefs of Staff saw D.D.'s broadcast. They send in a few squadrons and an AWACS to help, much to the surprise of Tasha. Who's this AWACS?
That's right, AC5 fans. The Yukes brought in none other than Oka Nieba.
Oka Nieba: << La la la! Listen to our beautiful voice! This is AWACS Oka Nieba, that means "Sky Eye" in your language. I've been ordered here by Anatasia's mother, Air Marshal Severskaya, and brought some of her old comrades too. >>
One of the squadrons that flew in was Tasha's old acrobatics squad, Team Zvezda, flying in Su-27/33/35S with their bright red & white livery.
They weren't equipped for combat and only chaff/flares, but their lack of weaponry greatly reduced weight and thus made them more agile, so they could do more acrobatic maneuvers to help distract the enemy drones. They speak on comms, expressing they're proud of Tasha after seeing what she was doing all this time thanks to D.D.'s broadcasts and social media updates.
Tasha: << You... you guys... >>
Tasha tears up on comms, seeing her old acrobatic team members and flying alongside with them again. And she was able to keep her promise to herself that she will never pull the trigger again since the end of Mission 30.
The rest of Joker Flight, Team Zvezda, and the other Yuke squadrons deal with the drone copies and to prevent them from sending any more. Which left Rex to finally fight the main dead-copy Tewy one-on-one and engage her in Ace Combat.
TGT X-40
MOON 11/SELENE
The main dead-copy Tewy then pleads with Rex on comms, since her actions are not of her own will, but she can at least speak.
Dead-copy Tewy: [[ Hand of Hope, I'm asking you to grant me passage to Hortus Regis Alti. Would you please? ]]
< YES | NO >
...
After a grueling dogfight, tougher than facing Shadow 22, Rex finally shoots down the main dead-copy of Tewy. She thanks him one last-time before her voice dissipates in static, and the drone explodes. Cope chimes in.
Cope: << Rest easy now, Tewy. Your Nightmare is now over. >>
The tunnels to the underground Enso Order facility are suddenly now open, the Sotoan Enso defectors held the door closed as long as they could, and a few drones fly in to destroy the facility and Rex flies in after them, alone. Déjà vu of AC7. This is where the the main theme OST of Ace Combat 8 plays, I'm thinking of the 30th Anniversary version (https://www.youtube.com/watch?v=iOjAO1qMBy0).
The drones wreck as much of the underground infrastructure as they can, however Rex shoots them all down through these tight corridors. He destroys them just before they can deal a real critical blow to the entire facility itself, however they do just enough damage that part of the tunnel starts collapsing, and Rex has to escape.
The exit is in sight, and the tunnel is collapsing all around Rex. Everyone around is watching a section of the underground facility collapsing inward on broadcast or in-person. The music stops right before the climax section. Radio chatter chimes in like crazy.
XO Pike: << Joker 1! >>
Dealer: << Joker 1! >>
Oka Nieba & Yuke Squadrons: << Wings of Theve! >>
D.D: << Hand of Hope! >>
Rosie & La Chanteuse: << Hand of Hope! >>
Coster: << Rex! >>
Kate: << Rex! >>
Tasha: << Ray! >>
Cope: << Go. Take back what's now yours. >>
And when Rex finally escapes the collapsing tunnel at the last second, flying back into the sky...
CERTE! PER CAELUM VOLA
ESTO LIBER, OH ESTO LIBER
VOTA RELICTA IN POSTERUM SERITO
FI VENTUS
CERTE! AETHERA DOMA
UBIQUE, OH UBIQUE
VOTA RELICTA IN POSTERUM SERITO
.....
Then the surviving Sotoans of the old capital look up to the sky, seeing that the Terminus Fingers himself had saved them. We also see the camera shift to the people of Ibirsh, and because of what they saw on social media, they too finally put their hands to the sky, to Hope itself.
All the drones have been disabled and destroyed. The ally Yuktobanian squadrons stay around to secure the airspace, under orders from Air Marshal Severskaya, as allied forces coming internationally are coming into the Sotoan old capital to secure the Enso Order facility, thus sealing the organization's fate.
Joker Flight takes in one last squadron formation. Just like in Mission 1 where it showed the intro card of their squadron, it instead says "Hand of Hope". They then fly off back west with the sun shining above them, back to the FCU, back to where everyone is waiting for them.
The story then ends as normal.