Parade rainage time, I'm afraid.
The thing is... it didn't make sense. "Hey, Alpha 1, the Vasudans are shooting at us, so let's run away!"
I understand that you're making a mini-campaign and so can't spend a dozen missions detailing the current state of Terran-Vasudan relations during the twenty-seven years since the Second Shivan Incursion (and it would appear that the Terrans and Vasudans haven't been updating their ships in quite a while)... however, simply blurting out "Vasudans are bad guys now, 'kay?" without background or reason just lacks... effect.
If you can't fully explain the sudden hostility on the behalf of the Imperium and thus allow the mission to make sense, then go for the opposite effect - disorientation, surprise, befuddlement. Have Alpha go out as a welcoming committee for a Vasudan destroyer plus cruiser escort, only for the Vasudans to suddenly open fire and cause chaos and panic as they rip through the unprepared Terran forces...
As it is, without any element of surprise, nor any explanation of the matter, it just seems like you stuck the Vasudans in there for the sole purpose of the player having someone to fight.
And names: Geno, Meno and Cento? GTC Horus? GVC Aten 11, 12, 13, 33, 34; GVCv Sobek 28, 29, 30; GVC Mentu 31, 32? Please. Use
real-life names - don't just throw random syllables together, don't use pre-existing ship-class names and don't use the standard FRED ship names because, surprise surprise Cilla, they're not very good. I'm also somewhat baffled by your use of 'Xulu' and 'Escort' as wing names - of course, you can use such wing names if you want, fair enough, it is twenty-seven years on... but I don't know why you used Roman numerals as well. Why not use other wing names, instead of just repeating 'Xulu', 'Xex' and the like?
Balance is off somewhat, I would say. On Medium, Alpha and Beta got wiped out, leaving me to fend off multiple Taurets and Serapi... not to mention defending the Cento from Sekhmets. I survived, but only because I'm competent and can mash the keyboard often enough to dodge most incoming fire; however, survivable doesn't necessarily mean appropriate.
The atmosphere wasn't particularly well-defined. A Vasudan destroyer has just wiped out an Arcadia installation - and not only does GT(V)A Command fail to send reinforcements to kick the living daylights out of the damn Zod, but the survivors seem curiously blasé about the sudden violation of the otherwise strong Terran-Vasudan alliance, the destruction of their curiously under-manned installation (only eight escape pods?) and the death of all those on board the poorly-named Horus ("Haha, the Horus is dead, they suck?" I thought you weren't supposed to speak ill of the dead?). I would have thought they'd be a little more frightened, scared, upset... something other than jovial about a couple of thousand deaths. 'Course, the mission isn't very heavy on the dialogue in any case.
Just a few thoughts.