Interestingly, I never intended to make a TC when I started on Frozen Heart. I actually wanted to use EV as a way of planning my novels, with the constraints of real time and a 'real' map.
At first, I made just one ship - the Tachyonic Fighter - which initially had the graphics of the Lightning, because I'd never done any 3d graphics and didn't know where to start.
I then wondered if it would be possible to put my story in as a plugin - really for my own amusement. My first real problem was that the novel uses a lot of flashbacks or people telling other people what had happened in the past. Obviously you can't have flahsbacks in EV, so I had to start the story much earlier, which is why it begins with the death of the character's father, goes through university, meeting Emile, the Devorian civil war, the Aphrodite dig, the Frozen Heart itself.
On the way Katherine Baxter invaded the story, and demanded that entire mission strings be devoted to her.
In one of the early drafts of the novel, there was action aboard a derelict space ship. I took this out, because I thought it was too derivate of Andre Norton's the Zero Stone (a favourite book when I was a teenager), but the derelict made its way back into the plugin story line, along with my archaeology tutor from my own student days, by another name and with another resume.
When I'd got as far as the end of the novel, I had too many loose ends. What would happen to Katherine? Would the character ever get it together with Alana, and why would he want to with Kath still on the scene. And then there were left over bits from the earlier New Venus thread. This resolved itself unpleasantly, so I didn't want to leave it there.
And then there was Lindi van Roth, based on the character of Amelia Earhart. Lindi had to make a final appearance, and there was still a black hole to be dealt with.
On the way, various planets had to be invented, and all the descriptions for existing planets rewritten so as to refer to the Magellans and the Rigellians, not to mention the nine worlds and the non-aligned worlds.
This also meant that the ship descriptions had to be redone, and then I discovered banking, which meant I had to make all the ships again.
By this time I was fed up with the EV landing pics, and I'd just got Bryce 2 with a magazine subscription. So all the landing pics had to be redone, and then all the planet pics, because I felt the original ones looked a bit flat.
I was also concerned about the general non-astronomicalness of EV, so I got out a star atlas and reworked everything again, including all the solar system stuff.
At that moment, I was about to release Frozen Heart, which had been in beta for some time. But then EVO came out. What had begun as an add-on had now become a very large universe-shift. I either had to import all the remains of EV into FH in order to make it EVO compatible, or I had to replace them. I wasn't sure that importing them would be legal, so all the vestiges of EV were then replaced with FH stuff.
What I'm saying is that no planning was involved. It grew organically, as the story grew. This is one reason why I'm always sceptical when someone comes along with their grand plan for a TC.
That said, and this goes back to the production values thread, I did have some fairly firm ideas about how I wanted the universe to be. The story had to be brighter than anything that EV (or EVO) had produced. But, aside from saying that Katherine was really really really beautiful, and that the tachyonic ship was really really really fast, there didn't seem much scope for it. The solution I chose was to make the overall scenario much darker to give some space for contrast - like the white in a photograph of the sun on a dark sky, which isn't any brighter than the white on photographs of white sheets of paper, but seems searingly bright because the rest of the image is so dark.
I also wanted a fairly strong thread of destiny and moral choices and the supernatural running through as an undercurrent, and surfacing at critical moments. Likewise, I wanted the archaeology stuff to stack up and be interesting on its own account, discovering more about ancient civilisations.
I also had some firm ideas about how I wanted things to look. The outfits especially had to be much more detailed, and I wanted people living on the planets, which meant they had to have buildings on (which EV and EVO didn't have for the most part). Likewise I wanted people appearing in the outfits, and a more human feel to the ship descriptions and the missions.
I also wanted to include some real challenges which were different from the kinds of challenges in EV or EVO. These ranged from purely intellectual challenges, like the anagrams, finding the University Labs, and decyphering the inscription on the ring, to combat challenges, like the asteroid fields and the Hawk, and, ultimately, the Black Hole.
Finally, I wanted to give the player the ship that everyone dreams of, and yet still make the game play as difficult as possible.
Various other surprises came up as solutions to problems in the plot. Tesken Alpha had to have two ports, but this was not something EV supported. Several cups of coffee later, I realised it did.
Likewise, I wanted concurrent missions so that the player could choose which threads to follow, but still had to complete groups of threads before moving on to later points in the plot. This wasn't really supported by EV, but with enough tedious logic-table tweaking it was kind of possible.
The final production value was that I felt that space itself should be dangerous. So, hence the asteroids, and the black hole, and the gas clouds, and the mines in Aurora.
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M A R T I N T U R N E R