Right. So, Mantle was envisioned as a...probably something like forty-mission-long campaign. What I released was just the first section -- it was never intended to be the complete story; I just released it the way I did because I wanted to put something out and it made for a decent stopping-point.
Now, as for what the rest of it was going to be like...
The story picks up with the Apocalypse and its crew in the system designated "Eden". After a few days of regrouping, Alpha wing is sent scouting. Deeper in the system, they find a debris field -- the remains of a planet. Investigating energy signatures, they come upon another Knossos device -- heavily damaged -- and two groups of primitive alien craft engaged in battle. Fearing that the second Knossos will be destroyed, potentially trapping them in-system, Amenophis orders the alien ships wiped out.
They report back, and Runihara sends out some more scouting missions to capture one of the alien craft so they can gather data. It turns out that the aliens are a species of quadrupedal reptiles who live in the debris field -- it used to be their homeworld, but it was destroyed hundreds of years ago during a huge conflict. The two warring factions are still carrying on their battle in the ruins.
The aliens are quite technologically backward compared to Terrans and Vasudans. They have no subspace capability, no shields, no energy weapons -- just rocket engines and mass drivers, basically. Runihara announces that these aliens must be blasphemers, and that the Shivans brought the Apocalypse here to destroy them.
The HoL launch an extermination campaign against the hapless aliens. It goes very easily, even after the two alien factions stop fighting and join forces. The only hiccup for the HoL occurs when the aliens manage to ambush and capture the Witness (that's the Bes-class freighter). Regardless, the Apocalypse wipes out the last of the alien habitats, secures the Knossos, and jumps through.
A tiny number of the aliens evaded detection, however, and they launch a strike against the Apocalypse in subspace using a light carrier rigged up with the Witness's subspace drive. But the HoL kill them anyway.
So the Apocalypse makes it back out into the next system, which, surprise surprise, is full of more Shivans. Including the same Lucifer that was chasing them before! So basically, the Eden system was this inaccessible island with only two nodes out, both of which were blocked by nonfunctional Knossos gates. But outside of it, everything is interconnected.
Anyway, they fight the Shivans some more. They start capturing and retrofitting Shivan fighters to replace their own destroyed craft -- then Shivan cruisers, then corvettes. Eventually they actually manage to attack and disable the Redeemer (the Lucifer-class), and then they gut the thing and stick its shields and armor and beams onto the Apocalypse.
They dick around with the Shivans some more, and go through a couple more systems. They run into some Sathanases, run away from them, and -- having hastily jumped through a subspace node -- they find themselves in the outer reaches of the Sol system, with the Shivans nowhere to be found.
Naturally, the HoL proceeds to murder everyone in sight. This goes on for a while. Amenophis starts to lose faith a bit. Maybe Dakarai dies or something? I dunno. Anyway, the Apocalypse blows up everything and then glasses Earth. This is basically the final combat mission.
Then -- well, I didn't have this planned out all that specifically, but the idea is that the player is meant to think the HoL are obviously delusional, and that they're spinning this whole grand tale about how the Shivans are shepherding them around when clearly they're just trying to kill the HoL like they try to kill everyone. Somehow or another, this idea would be driven home in the aftermath of Earth's destruction -- maybe with Amenophis renouncing the HoL.
Then a huge armada of Sathanas juggernauts shows up out of nowhere and starts talking to them, telling them that they've passed the test and the Shivans are going to take them into their fold.
So the campaign could have ended there, with a huge orgy of destruction followed by a stupid twist. There's another idea I came up with, though, in an attempt to make the whole thing at least somewhat thematically cohesive...at the cost of being an even stupider twist than the last one. In that version most of the same events would happen, but spooky stuff would start showing up during the last combat mission. You'd finish the mission, but then you'd somehow be unavoidably killed, and the mission would reset -- but the characters would remember the first attempt. This would happen a few times, and the whole thing would be really surreal. And then eventually the Shivans would show up and start talking.
The Shivans would reveal that things aren't quite as they seem. See, during the second-to-last mission of the released section -- the one where you're escorting the Apocalypse to the node while all the bombers ever are trying to kill you -- the Shivans had actually jumped all their capital ships in at close range and disabled the Apocalypse, along with all the fighters and other ships. Then they captured all the HoL pilots and crew, brought them aboard the Lucifer-class, and stuck them in a simulation where they basically let the HoL do everything they wanted to do, in an attempt to show them how empty and pointless it was. It didn't take at first, but they've been in the simulator for years -- running through the same series of events, over and over.
See, the Shivans in general have the goal of destroying all life, albeit in a somewhat roundabout way -- but the ones in Gethsemane are a breakaway faction, who no longer share the values of their brethren. They've decided to recruit the Hammer of Light (for some reason) as a guerilla force to use against the main Shivan faction, and did all that stuff with the simulation in order to teach them what they should value.
The HoL finally comes around and accepts the offer, probably. Except Runihara, I guess. He probably dies somehow. Also maybe there were some people who died during the later parts of the campaign but are actually alive because it was a simulation? Or vice versa? I dunno.
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So that's what it was going to be like. You can probably see why I'm not super invested in finishing the campaign: it never really goes anywhere. All the stuff with the warring aliens, and then the HoL starting to use Shivan tech, is obviously about the HoL symbolically becoming the Shivans -- taking up the mantle, if you will. But I struggled to fit that into any kind of larger thematic framework. After all, the HoL becoming Shivans is a fine idea, but it's pretty one-note -- that alone isn't enough to sustain a whole campaign, not without some kind of punchline to it.
The whole destroying-Earth thing was conceived as a sort of black-comedy type deal -- "those wacky doomsday cultists"! But that didn't fit the tone of the story all that well, and over time I kept trying to figure out how to give it some kind of actual meaning. I didn't really want the story to just be "the HoL get really good at killing and kill a whole bunch of people, the end". But the best I could come up with was that nonsense about rebel Shivans teaching them the meaning of friendship by showing them how unfulfilling simulated genocide was.
Oh, and I was also sort of wanting to incorporate this into my larger ideas for the FS universe, which don't involve Earth getting suddenly glassed by random Hammer of Light lunatics from nowhere. That was part of the reason for the simulation thing.
Anyway. Maybe there'll be some interesting discussion of this. I think the alien arc was a pretty solid concept -- a reenactment of FS1 with the HoL as the Lucifer fleet. I had plans for what ships I was going to use, too. And the whole "stealing all the Shivans' stuff and retrofitting it" bit would have been fun from a gameplay perspective -- getting cool new loot is something I really enjoy in FS campaigns. But I don't know if I could have spun it all together into a satisfying story, so I think maybe it's best Mantle stays where it is.
Oh, and clearing up one quick thing: I'm not sure if I made it clear in the campaign itself or not (well, obviously I didn't make it clear enough), but Abdaraxus Clade isn't a person. It's a small group of Vasudan engineering savants that serve aboard the Apocalypse. The idea is that some Vasudans innately have these bursts of crazy high-level skill in certain areas, and so you get stuff where a Vasudan will go into an engineering trance and then end up with some awesome new piece of technology, or an unreasonably quick repair job. I thought it was a cool idea, and also a good way to handwave how easily the Apocalypse seems to deal with technology and logistics.
I was even thinking of trying to incorporate it into gameplay -- have Amenophis be a battle savant, who could do this bullet-time thing. I didn't get very far trying to implement it, though.