The following is a list of Shout Outs made inside a mecha action game named Project Nimbus.

Ace Combat

In Mission 1, your CO introduces his callsign as "AWACS Dragon Eye", mentions that it is his birthday and asks you to give him a victory as his present.
In Mission 9, Thermopylae, your wingmen are named Mobius, Nemo and Rena.
As a whole, the entire game's story parallels Ace Combat 5: The Unsung War; a war is kickstarted between two nations, a clandestine conspiracy aims to ruin both nations, a president wants peace but is kidnapped to keep the war continuing, and a protagonist faction—MITHRIL in this case—goes rogue for the sake of peace. Last of all, the finale, Act 4, is all but a reenactment of AC5's mission where two sides once at each other's throats are now fighting together, and the final boss battle pits you against a squadron trying to stop you from destroying a descending satellite.
The Children of Fallen Nations can be seen as an Expy of A World With No Boundaries, both being Big Bad terrorist groups who fight the countries responsible for ruining the lands they lived in.

Armored Core

All Battle Frames (minus the M1 Guardian) can perform quick-boosts, just like ACs.
The whole 'humankind moving into the skies' plot is one big reference to the Cradles.
The Overbooster used by Andrei's S37 Custom is similar to the Vanguard Over Booster (V.O.B.) used by White Glint.
During one of the missions, you go up against a pilot by the name of Strayed, who doesn't speak.
The Children of Fallen Nations are actually AIs made by humanity meant to fight in their war, now wanting to end mankind for their endless warring. This makes them similar to Reaper Squad, who are manmade clones bred for war and now fight for mankind's demise.

GCTX-01 Mirai, the game's spotlight Battle Frame, is similar to the Strike Freedom Gundam both in terms of design and function. As for its ace pilots, Mirai and Morgan, you could say they're a collective incarnation of the White Devil.
UCN and CFN, the world's major superpowers, each possess their own orbital elevator.
Andrei and his red S37 Terminator which is faster than a normal S37. The mission you face him in is named Krasnaya Kometa, which, when translated to English, is "Red Comet".
Whenever Mirai and Yuliana fight each other, their respective Battle Frames experience a drastic performance boost while glowing bright red or bright green.
In the final mission of the game, the Children of Fallen Nations have decided to drop a massive Kill Sat named Testament on the planet.

The mission Comatose is eerily similar to the aftermath of the Third Impact.
When Hive-class aliens die in alien survival mode, they emit a cross-shaped beam of light.

Several Battle Frames are named after real-life fighter jets.
The storyline shares many similarities to Call of Duty's Modern Warfare series, from shifting POVs, introductory mission briefings, and someone provoking the UCN and CFN into waging war against each other using similar methods to "No Russian". There's also a Well-Intentioned Extremist American general who turns traitor for what he believes is for the sake of his country.
"That's no warship. That's a Battle Frame!"
Each update during the Early Access phase are named after Japanese World War 2 warships, which is likely a nod to KanColle being popular at the time.
The player character in Skull Squadron's sections has the call-sign Skull-1.
This wouldn't be the first time that an organization named MITHRIL had an advanced warship that launched Mechs into battle.
During the mission to rescue a VIP in the Pentagon, one of the allied ground soldiers say, "Stop acting like that blue cat thing!"