This would be a side-story project similar to the likes of Bachi Bachi and Morphworld, focusing on characters that appeared previously in the core Aozora series while having next to no connection with the title character and still set somewhere within the Aozora world.
In this case, the focus would be on the super soldier android Rizer, whose first appearance in the series' lore would be in Bachi Bachi as a rival character to Bachi. He was created as a full-on homage to the Metal Gear (Solid) character Raiden in terms of his character mold and fighting style, but he has a different characterization and is a full blown-on combat mech instead of a human later reconfigured into a cyborg. He was created in 2017, and the motivation for his creation, while going back as far as 2016, was sparked when I met Quinton Flynn, Raiden's voice actor, at EMCon that year. I then begun developing Rizer's Wiki page and got him designed by artist NRGart7, resulting in this:
Many of the design choices seen here were done to deviate Rizer further from Raiden, examples including the yellowish color scheme, the bottom jawline being changed into a shield or guard of sorts, an overall more armored up appearance, and a personal magnetic "cyber-sword". This had led to Rizer having his own unique set of tricks, such as tossing his sword forwards before using magnetics to retrieve it on the spot, though otherwise he's still fast and can perform rapid sword slices within only moments. And that's how his characterization went for a good while.
A year later, I decided to give Rizer a side story of his own to flesh him out, at the suggestion of an artist that took a liking to the character: Heoh Kim. Since I figured the story would have been a bit dull if it was just Rizer, I decided to have Kim design up a human companion for the armored robot.
After throwing around some ideas, we came to the idea of making a story that served as not only a side-story for expanding Rizer, but also a full-on semi-tribute to the Metal Gear franchise, leading to the creation of Snayro down below.
As with Rizer to Raiden, Snayro was made a homage to Solid Snake, with the typical differences in color scheme, personality, and fighting style. Snayro, in this case, sports a more uplifting and friendly overtone compared to Snake while still being on the smug side every now and then. Compared to Snake's reliance on stealth, Snayro gets down and dirty with swordplay much like Rizer, playing more defensively as he's a human loaded up with heavy armor and lots of different tools and gadgets, thus he can't get himself into as much danger and risks as Rizer can.
The project/idea would form into Rizer: Unleashed, a hack & slash stylish action game with multiple different scenarios to play through- one with each character, and a third which adds emphasis on co-operative play by having two players, either through a network, LAN connection or good old split-screen, control each of the two characters in one big conjoined plot that results in the true ending (though if one prefers playing solo, the true ending is also achievable by completing the stories of both characters).
Rizer's story contains homage stories more modern entries in the MGS series (most notably ones that otherwise focus on Raiden) while Snayro's harkens back to older entries (those that focus on Snake). Otherwise, the stories of Rizer: Unleashed would be written from scratch and more PG-13 in tone compared to the kind of story you'd expect in Metal Gear Solid. That said, the stories would still have a dash of dark and mature compared to your typical Aozora plot.
I'll probably go more in depth with this idea at a later date, but for now I think this should give you an idea of what the story would evolve into.
