Why arte the Doomsday missiles from the Final Frontier mod not in the Star Trek mod? In a lot of episodes, there is weaponry capable of destroying planets. A way to implement it in the mod would be adding two units: Doomsday Weapon and Doomsday missile:
Doomsday Weapon is a weak, slow ship (2 strength and speed or something like that), capable of carrying three doomsday missiles, while the missiles themselves are the same as they are in the Final Frontier mod. Both should be pretty late in the tech tree, in the DS9 or VOY era, probably.

If you add the Xindi in version 3.0, they could as their UU have these units, but on a much earlier tech (The same way as in vanilla civ, the Sumerian UB is on Priesthood, while its generic version is on Code of Laws)

They were originally, but a lot of people were didn't like them. The part of the tech tree the came in at (Tactical Guidance Systems) is later now that the ent era was expanded.

They may work quite well as a Xindi UU. The nuke effect used is currently used only as the meltdown for the Geological Power Plant (I never removed the modified onNukeExplosion).

The problem with the Doomsday missile (nuke, as is) is that it can strike anywhere on the map. (This could maybe be corrected with a limited range.)

I believe in the Final Frontier mod it has a range of 5 tiles. If you include it in this mod, you should perhaps give it only one tile range, as planet-killing weaponry always is in orbit when it strikes in Star Trek.

EDIT: If it's range is only 1, the unit carrying the weapon will get hit by the blast. So a range of two or three would be better.

You're probably correct. (Personally I found the nuking of my best planets kind of annoying, which happened as soon as war broke out. Your solution sounds pretty good; at least it allows some sort of defense, as soon as a Doomsday carrier is spotted.)

Civ doesn't allow you to nuke an area if a friendly unit is caught in the blast. And it doesn't allow you to see what a unit is carrying either (so you still would be unable to see them, unless I could figure out how to change it).

You would just give the nuke a specialunit type, and have it so that only specific vessels could carry them. Basically have it work like the Missile Cruiser & Tactical Nukes in BtS. Of course I'm not sure if the AI would know how to deliver the payload then. Does the AI have good logic in it for delivering Tactical Nukes in BtS?

Well, they use tem a lot, though I don't know whether they ever use missile cruisers in vannila civ.

If you have a Doomsday Device it should be the Doomsday Machine. Really, nothing else works. Of course, it destroys planets without any sort of missile and was highly resistant to attacks. How one might make something like that work in Civ I don't know. But anything resembling a planetkiller in Star Trek, what else would one make it?
Now a list including Genesis, Red Matter, and Trilithium is replayed back at me. To it I have but one response: "They say there's no devil, Jim, but I saw it. Straight out of Hell, I saw it!"

I prefer to think of it as making the planet uninhabitable rather than destroying it. Not that that's reflected in the current graphics (it changes to a sun).

I prefer to think of it as making the planet uninhabitable rather than destroying it. Not that that's reflected in the current graphics (it changes to a sun).

It could be that the planet is so irradiated that it glows. Making a planet uninhabitable is in reality a more logical thing to do if you want to conquer the system, btw, as the orbits of the other planets will get screwed up when a planet is completely destroyed because of the changing gravity field in the system. It would also cost a much lower amount of energy. (Not that any of that is very relevant to this mod)