I'm thinking, do as BSG and start the series with a 2-part 2h each mini-series. In my view, it would start aboard an Orion class destroyer, or perhaps an older design, based in Ross 128 system. Lets call it GTD Powell (for lack of a better name right now). The pilots would of course be the leading characters. The command officers and support crew aboard the destroyer would be secondary. The main pilots are of promissing skill but haven't faced real heavy combat yet. They do have to engage Vasudan scouting wings, and perhaps get a moment for the hot-dogs in the squad to show-off with a victory against a small ambush with bombers and an Aten or too.
Then, things quiet down a bit, and there is some odd activity observed on the part of GTI. Perpahs a few of their ships are seen in the system, heavily dammaged but still functional. They drop in at GTI Riviera to make repairs, saying that they got caught in a Vasudan abush. The GTD Powell also drops in for some supplies and some of the pilots head over to the station for a bit of R&R and encounter a few of the GTI crew. The GTI's jr. officers are acting real nervous and even pettrified. They manage to get a Lt. alone briefly in a bar and he warns them that they need to get out of the system as fast as possible. He can't tell them more as a supperior officer interrupts them and calls the officer "McCarthy". He tells McCarthy that they don't have time to chat with rookie pilots, and that their cruiser is on a tight schedule. You can hear the stress and threats in the undertones of the conversation. The GTI ships are only there briefly, before they split and reports have them heading into Delta Serpentis at basically break-neck speed. The pilots are then rather suspicious but return to their duties. They report their concerns and McCarthy's warning to their own CO, but he says that he contacted GTI himself with the same concerns, but they replied that there's nothing to worry about and all that. The CO then tells them to stop trying to push their noses into things, and sends them out to reconnoiter a Terran cruiser that hasn't checked in yet.
They find a completely trashed Leviathan class and terran debris all over the place. They think that the Vasudans are responsable, but manage to come accross either a cripled escape pod or fighter (if the former, only one person is aboard). They call in a support ship to recover it. This support ship is not equipped for rearming, but for craft boarding. One of the main character pilots docked to the support ship on the other dockpoint and boards it and is the first into the cripled fighter/escape pod. The survivor is completely nuts, like the pilot in the FS1 intro but worse. He's like all catatonic and spouting nonsensical phrases, think River from Firefly, but less criptically logical. He manages to utter a few erie phrases about.... what is obvious to us as the Shivans, but no-one undertsands. Scans of the cruiser's debris indicate that it was destroyed by some kind of high-yield torpedos. They suspect that the Vasudans have developped some new weaponry, but are puzzled that no Vasudan fighter or bomber debris was detected in the combat zone.
Some time later, word comes of an engagement between Vasudan and Terran forces, and one of the squads is sent in to reinforce. When they arrive however, all they find the the destroyed wreckage of both fleets. Both Terran and Vasudan fighters and cruisers are completely destroyed, and some of the cruisers are even showing complete holes punched through them, obviously from the Lucifer's beams. They also read a faint trail of radioactive fuel indacting that a Terran fighter managed to limp away from the engagement. They follow the trail heading towards GTI Riviera, and manage to catch sight of the massacre at long range. They'd powered down their systems to avoid attracting attention. They're ordered to get out of detection range and jump back to the GTD Powell to report personally on their sighting. Upon jumping back to the destroyer however, they find it under full assault from the unknowns (Shivans, obviously), but the Lucifer isn't present. Say, a cruiser wing and perhaps a Demon, but lots of bombers. They do their best to try to fight off the attackers, but you get the standard "there's some kind of energy field blocking my shots" and "my radar can't lock on" and "who are they", comments from pilots. The Powell takes a pumelling and is completely unable to escape. As it takes more and more dammage, the CO manages to send a message to the pilots that they'll try to launch escape pods. He also says that someone has to get word out about the alien threat. The bridge then takes a direct hit, killing all present. Some of the pilots try to defend the few launching escape pods, but are taken down, followed by the escape pods. A Shivan warhead then takes out the entire launch bay, so no more can launch. With GTA pilots getting splashed all over, and no senior officers present to give orders, some of the pilots decide that the only people that could get away to warn the rest of the rest of the fleet about the Shivans, would be them. A few of the pilots manage to escape the engagement, jumping to a hastedly-decided location away from the combat. A few who are late in arriving, report seeing the Powell being destroyed. In all, about a six Apollos manage to make it out. Most of the pilots are scared out of their witts, but one of the main pilots manages to calm them down and states that they need to carry out their assignment and warn the GTA of the Shivan threat, by jumping to the Ross 128 communication terminal (a Faustus class) and send the transmission from there. They jump in to find that it's already been knocked out, before even the GTI Riviera attack. That leaves them somewhat of low spirits, but continue to loiter around. The situation is compounded by the fact that without a destroyer or cruiser to jump alongside, they can't jump out of the system and escape.
Over time, additional GTA fighters and bombers jump in, survivors from other engagements. Some are experiencing shell-shock. Fortunately, they manage to all keep each other going. In all, they end up with 15 or so craft, made up of Apollos, some Athenas, and even a few Angel scouts. Corollating the times of contact with the Shivans, they realize that they're heading towards the location of a known unstable node to the Ikeya system. The Angel pilots are sent out to see if they can confirm this. They find the bulk of the Shivan fleet jumping out, including a glimpse of the tail end of the Lucifer entering subspace, but not enough for a full ID. There are still Shivan forces in the system causing havoc. Some of the pilots return to the new staging area, now in close orbit of a gas giant to conceal them, indicating that they've come across a few civillian ships that have been crippled or heavily dammaged. The group then manages to get some of them fixed up enough to jump, and proceed to rescue some of the civillians.
The head pilot also recalls that there's a Fenris class cruiser undergoing an overhaul near a supply depot, and considering that its out of the way it may have been overlooked. Using the civillian crews and a few GTA engineers rescured from a transport, they manage to get the cruiser working and even partially armed. During the repair process though, they're surprised when a group of Vasudan fighters jump in, with Shivans on their tails. Fortunately, there are more Vasudan and GTA fighters than the Shivans. There are a few Basilisks in there, and concentrated fire from the many fighters manage to punch through the shields on one and destroy it. It's squad-mates withdraw, but the concern remains that it won't be long before the Shivans return, now that they know where they are. Using some extra weapons and supplies at the depot, they manage to get their fighters almost fully repaired and rearmed. Fortunately, the Vasudan fighters agree to join forces with the GTA team.
The Angel scouts are sent ahead to check on the status of the Delta Serpentis jump node, which is the only real escape route, to see if its clear of shivan activity. As they arrive, no Shivans are detected, but they catch sight of a Terran science cruiser about to jump through the node. They identify it as the GTSC Einstein and are just about to hail it, when it jumps. As they're ponding this, a Shivan fighter squadron and a Cain cruiser jump in and take up a blockade position. The scouts then jump out before they're detected.
Knowing that the Shivans both know where they are, and where they're going, they're between a rock and a hard place, but decide to try runing the gauntlet never the less. Fortunately, the supplies at the cargo depot also contained a few Avenger prototypes, intended for testing on the GTI Riviera's experimental deflector system, but there's very little ammo. for them. Using the cruiser as bait, they manage to draw off the Shivan cruiser from guarding the node, so that the few remaining civillian ships can enter the node and jump out. Then, the cruiser and fighters have to punch through the Shivan defenses and keep the cruiser alive and functional until it gets to the node. They manage to get past the cruiser and enter the jumpnode, but they've expelled all their Avenger ammo. The Shivan fighters follow them into the node, and its at this point the fighters find out that the Shivan's shields don't work in subspace. Fortunately, the Terran fighters still have ML-16s in their other bank, as are the Vasudans with their VLL-9s, so they manage to slpash nearly an entire sqadron of Shivan fighters, though they have to deal with a couple of nasty wings of Dragons. Fortunately, they succeed in destroying all persuing fighters and emerge into Delta Serpentis. They report to the local flagship and give their findings, while the Vasudans are taken into custody temporarily. The pilots are briefing the Admiral in his office aboard his flagship. He is treating them and their story with a certain degree of patronising skepticism, but just then an officer enters the room and whispers something to the Admiral and hands him a report. The report is of the destruction of the GTSC Plato and the reported engagements with the Shivans in and around the Beta Cygni system. The pilots are given decorations for their actions, and the Vasudan pilots are granted safe passage home as the cease-fire is in effect. The GTA pilots are then reassigned to the GTD Bastion for their tour of duty. They may have expected their first heavy combat to be against the Vasudans, but that conflict is now on an indefinite suspension, while the Great War takes center stage.
There would be time for character developpment and conversations before the attack and during the lull after the loss of the Powell. The 1st part would cliff-hanger just as the pilots jump in to find the Powell under attack. There would also be some ambient discussion about Opperation thresher in Antares and the Galatea durig the early scenes. There'd also need to be time to acquaint the viewer (assuming that this would be made so that a total FS Noob would be able to get it) with subspace, both in-system and inter-system, as well as acquaint them with the Vasudans and the war.
The pilots that escape this, would become the core main characters for the series, but they would be joined by crew-mates from the Bastion to take up prominent roles themselves. Some of the Vasudan pilots would also become recurring characters, with one of them eventually turning traitor and joining the HOL. Some of the Terran pilots that survived might also be called to the McCarthy trials to testify in his defence, only to be thretenned by GTI who wants to keep their involvement quiet. Furthermore, the Angel fighter pilots who witnessed the Einstein escaping from Ross 128, contradicting the official record, mention this off-hand to the first officer. He ends up mentioning this off-handedly to one of his trusted friends and officers aboard the Bastion, who ends up being a GTI spy and gets word back. GTI eventually sees to it that both pilots are killed in action, and all their personal data sufferes accidental corruption.
Later episodes would also cover the destruction of the Galatea and the Vasudan homeworld as a season finale (though possibly 2nd season). In fact, the seasons could end with the Acts from the game. Season 1 ends with the Lucifer making its dramatic entrance at the destruction of Tombaugh station. Of course, this rules out the possibility that one season equals one year of time, for the characters. Nothing new in that respect. Bomber pilots would be on loan to the Galatea's strike team against the Eva and also witness the destruction of the Galatea, while the fighter pilots try to desperately prevent the Shivans from making it into Vasuda... until the Lucifer arrives. The 3rd season finale would cover some of the pilots being sent off after the Lucifer into the Sol jumpnode. The rest are sent too, but the node collapses before they can make it in. Tellemetry indicates they succeeded, but Earth is completely cut off, possibly perminantely.
This would have a strain on the remaining characters, as they may have loved ones in the Sol system, so they're completely cut off, resulting in some expected emtional responses in season 4. However, there's verry little time to mourn, 'cause the Shivans are still mean and big and have lots of ships. Fortunately, they appear to have no reinforcements, and they start losing ground. But they also have to deal with rising tensions with the Vasudans as well as the emerging Silent Threat ark. When the Krios is destroyed, the GTA Provision Goverment orders the Bastion to join the Soyokaze in investigating and fighting the rogue GTI. They also manage to have McCarthy peroled from his penal colony in Beta Aquilae and brought aboard to help them track down the GTI. There might also be an oppertunity introduce Bosch, as well as his psycho side. The finale would feature both the final engagement agains the Shivans, when GTA manages to corale the remains of the Shivan fleet and sends in nealy everything they have to destroy it. During this emotional high after completing this however, they get a message from McCarthy indicating that he's discovered where GTI HQ is, and that they have to attack NOW. He knows that the Hades is nearly fully opperational, so he knows that they need to attack before it can be brought online. McCarthy manages to get a seat aboard the Orff, but that ship gets trashed when the Hades' beam guns come online during the engagement. The Soyokaze is the only other ship that could be spared and its taking a beating. Its up to the main character pilots to knock out the beams and take on the enless waves of hybrid Terran-Shivan fighters and bombers the Hades is throwing at them. Fortunately the Orff which is on fire and going down, manages to ram the Hades' reactor secton causing an overload. In the aftermath, various members of GTI that escaped are hunted down and taken into custody, while McCarthy is remembered in a millitary funeral. The pilots are then split up, getting promotions and assigned as squadron leaders on multiple destroyers and stations. In the final scenes though, the seeds of Bosch's future rebellion are sown, as we see him talking with a few GTI officials he apprehended, in private. We see him later in an office looking over some notes both on Shivan communication, technology, and even data on the Ancients. He then sets these aside and turns to a computer screen where he's filling out the after action reports for this incidedent with the captured GTI members. The form isn't complete, but there's one line that has "status of target: captured" written, with the flashing cursor sitting just after "captured". Bosch then backspaces over the last line and replaces it with "destroyed", and fills in the line below as "status of target crew: terminated". This indicates that he falsified reports to conceal the fact that he's hiding both the documents and the GTI members for his own purposes. He then turns back to the GTI documents and continues reading, as the screen fades to black.
How's that?