interesting. perhaps, if Hakase actually sketched that image himself, he could do a rough draft of what our fighters should look like realistically. might make up for some interesting future conversations!
Tesla figured out how, with the correct negative and positive electrical field, to defy and eliminate the gravity of objects (earth included). I am going to guess at some point the oil tycoons will lose their grip on earth and we will be able to delve deep into a technical renaissance where new energy and propulsion will be discovered. We will no doubt also figure out better ways to kill each other and make mass driver technology a ting of the messy past. What wonders await us.... well who knows... but sadly one only needs to delve into the past and even just a quick read on Nikola Tesla to see what is being held back from us.
My guess is that the saucer shape might be the best shape to take based on drag reduction or creation relative to mass. Missile weapons will 100% be a thing of the past, missiles are rather old tech and a huge waste of material and technology. When fighting in the depth of the void a extremely small projectile traveling at extreme speed (near light speed) would be more effective and a billion times cheaper and you would be able to store almost an infinite supply of ammo vs large cumbersome expensive unreliable and defeatable missiles, not even mentioning energy based weapons yet.
If this game goes for a real setting then it needs to take the path not yet taken and walk down reality lane. Fighting in space will look nothing cool like the movies. Space fighters will not want to dual role as earth fighters unless of course we go with designs without things such as a canopy, windows or anything that would add friction or be a weak point in re-entry. That is unless you take on the hard science of ion pulse or wave pull / field slip propulsion... and then you get a near arcade control setup. The one thing you cannot say is that you have the best space sim using technology as we understand it today 1K in the future.
diamonds are hard, but very, very brittle. not a good armor idea.
If you want no one to hurt you, layer Depleted Uranium and Boron Carbide on top of each other, and then coat your outer layer in grafold (folded graphine). nothing is getting through that. Except, like neutrons. or if someone shoots a small black hole at you. Those don't happen very often, though. At least not to me.
now, of course, you have to deal with waste heat. uhm, I just do armor, and your warranty is not valid if you stick anything outside you spacecraft. like Radiators. or your head.