If humans were to attempt to colonize a planet already inhabited by hostile intelligent shapeshifting humanoid reptiles, what kind of problems would they encounter and what would be the best method towards defeating them without destroying the jungle? The humans have energy weapons and the reptiles have similar technology. The planet is Pangea-Like and mostly covered in jungle.

There are about 50,000 Reptilian Warriors and about 15,000-20,000 human colonists. Both sides use DEWs (Directed Energy Weapons AKA Lasers), some of them use modern weapons such as tanks, rocket launchers, machine guns, and so on. Climate is tropical rainforest. Colonists came in multiple colonization ships. Reptiles are able to shape shift into other organisms at will. Humans are able to understand reptiles using translation technology and vice versa.

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    $\begingroup$ What do you mean by "energy weapons"? Why aren't they effective enough on their own? $\endgroup$ – ndnenkov May 31 '17 at 13:56
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    $\begingroup$ You'll need to add some precisions about your setup : number of forces in presence ? Tech level ("energy weapons" is quite vague) ? Climate ? How did they come there (different scenario if aboard a colony ship or a fleet of warships) ? Precise abilities of reptilians ? Level of understanding of said reptilians by the humans ? $\endgroup$ – Keelhaul May 31 '17 at 13:58
  • $\begingroup$ Directed Energy Weapon AKA Laser. Also photon pulse weapons. $\endgroup$ – Synergetic May 31 '17 at 13:58
  • $\begingroup$ It is unclear if you are asking how they could defeat the natives in your setup or if you are asking us to create a setup where they could given this as an outline. $\endgroup$ – ndnenkov May 31 '17 at 14:02
  • $\begingroup$ Edited Question to fit @Keelhaul's questions $\endgroup$ – Synergetic May 31 '17 at 14:14

(I could probably go into more detail on this, but it's already taken me an hour to write so this'll do for now.)

tl;dr: How can the humans win? With great difficulty.

What troubles would the human colonists encounter while fighting against them?

Your reptilians are shapeshifters. Ever seen The Thing? Shapeshifters are not only really difficult to fight, they're also bloody terrifying.

Consider a simple one-on-one skirmish between a human and a reptilian. The reptilian could turn into a mosquito, making him impossible to shoot (and potentially allowing him to infect the colonist with space malaria). He could turn into [insert whatever giant deadly predators your alien planet has]. He could turn into a sobbing human child, begging the soldier not to shoot, and while he wrestles with his conscience, another reptilian sneaks up and shoots him in the back.

Then you'd have reptilians disguising themselves as human commanders and giving phony orders, or disguising themselves as refugees/soldiers to infiltrate the colonists' camps, or turning into small animals to listen in on covert meetings (like a literal fly-on-the-wall), or turning into small animals to set up an ambush ("Hey, look at all those birds sitting up in that tree-- OH GOD THEY'RE ALL REPTILIANS")... you get the picture.

I once wrote a shapeshifter who could "heal" from injuries by simply shapeshifting into an uninjured form. If your shapeshifting reptilians can do the same thing, that's really bad news. You're looking at an army that outnumbers you by 3 to 1, can heal from just about any physical injury that isn't immediately fatal, and can be anywhere or anyone or anything at any time. I repeat: bloody terrifying.

So how can the humans win?

Well, if there isn't already a way for the colonists to tell who's human and who's reptilian (infrared, DNA scanning), they'll come up with one very quickly. Perhaps a system of ever-changing passcodes, or that old trick of asking questions that only the real person would be able to answer. @Draco18s suggested in a comments that every colonist be given a VPN dongle, and that gave me the idea of going one step further: an ID chip embedded under the skin. It would be difficult for the reptilians to replicate such a thing.

Once you've got the ID problem sorted, hold any and all important tactical meetings aboard one of your orbital spaceships. If you suspect someone's secretly a reptilian, fire them out the airlock. Heck, you could fight deception with deception: hold fake tactical meetings out in the open, knowing that the reptilians will eavesdrop on them, while holding your actual meetings up on your ship. The reptilians will act on the false info you give them, and then you can take advantage to plan surprise attacks of your own.

Finally, if you still can't overcome the reptilians' shapeshifting abilities or sheer numbers, just go down the scorched earth route: burn the forest down. Nuke it from orbit. You said in a comment that you didn't want to do this because it would render the land unusable, but in warfare there eventually comes a point where you really just don't care about things like that anymore: you just want to win.

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    $\begingroup$ If you have to ask your commanding officer a question "only she knows the answer to" every time she comes into the room, dem reptile-flies on the walls are gonna learn it all eventually. $\endgroup$ – Draco18s no longer trusts SE May 31 '17 at 16:42
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    $\begingroup$ True enough. What about the changing passcodes, how well would they work? $\endgroup$ – F1Krazy May 31 '17 at 16:52
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    $\begingroup$ VPN dongles. Every soldier has one. Confirming identity could be done with the user's smart-device. "What's your current code, Captain?" The asker doesn't know, the reptile can't know, only the computers know. The reptile would have to steal the dongle for anyone they wanted to impersonate, which would require incapacitating them, which might pose a problem. Hell, you could even DNA key the dongles. $\endgroup$ – Draco18s no longer trusts SE May 31 '17 at 16:55

Well, if humans are able to colonize planets, and lizards are not, then that means humans have much more advanced spaceship technology and thus can employ easy "nuke them from orbit" strategy. If lizards are also able to build spaceships, then it would mean that battle will be waged on totally different scale and this planet is not that important.

(Sorry Jake Sully and Pandora, u never had a chance:D)

  • $\begingroup$ The humans want to colonize the planet, not turn it into a nuclear wasteland. And yes, the Lizards are able to build spaceships, but that doesn't mean that the war will be waged mostly in space. The humans want the planet, and therefore will try to take it by ground/air. Space battles will be uncommon $\endgroup$ – Synergetic May 31 '17 at 14:49
  • $\begingroup$ the nukes doesn't have to be nuclear missiles necesarily. im just saying that spaceship technology will be key in this war. imagine that humans are trying to take over some lizard city or fortress. it will be heavily fortified with maybe walls and definitely with tons of anti-air and anti-ground guns and mines all over the place and so on. why would humans attack this fortress directly when they can just throw exploding stuff from orbit and then use army/airforce. in a universe like this you cannot have space battles uncommon. they will be the key. like in stargate or starwars $\endgroup$ – user38849 May 31 '17 at 15:01
  • $\begingroup$ Hmm, that would be useful for the colonists. This is probably the best answer I've gotten so far. $\endgroup$ – Synergetic May 31 '17 at 15:03
  • $\begingroup$ There are plenty of non-radioactive ways to perform orbital bombardment. Tungsten rods tend to be the go-to. One of those impacting the ground has a comparable explosion effect as a megaton nuclear warhead, if I remember correctly. There's a tech gap here. Deal with it from space, the ultimate high ground. $\endgroup$ – Draco18s no longer trusts SE May 31 '17 at 16:59

Block The Sun

Assuming the reptiles are cold blooded, the humans could block the sun, using huge amounts of smoke/ash/ something else for a period of days or weeks, the reptiles would have no way to heat themselves and they would die or be very weak to human attacks.

  • $\begingroup$ Good answer, but what if the Reptiles have some kind of machine that emits heat. They could just use it if they get too cold. $\endgroup$ – Synergetic May 31 '17 at 14:31
  • $\begingroup$ I'm almost certain that a civilization that has the ability to fight a war on equal footing vs a space-colonizing sci-fi species has discovered a way to warm themselves other than the sun $\endgroup$ – Raditz_35 May 31 '17 at 14:51
  • $\begingroup$ Exactly, blocking the sun would not be an effective attack. What about heating the planet? $\endgroup$ – Synergetic May 31 '17 at 14:57



Germs get strange in gravity less space and by strange I mean horrible. Grow as many diseases in space as you can, get your humans as immune as possible. Jungles will spread the diseases far and wide. You'd need to unleash as many highly infectious diseases as possible. If the reptiles become immune to one, let three new plagues take it place.

Induce Climate change

Frank Anderson's idea block the sun has merit, but doesn't go far enough. You need to create sudden planet wide climate change to create mass cooling. Not only could this cause massive problems for the reptiles, but it could also d-jungle the planet. (because fuck jungles)

You are in space and probably out of reach of them. Use it.

  • $\begingroup$ The diseasees would work, but what if after the humans kill all the reptiles, the diseases mutate and start killing everyone? De-Jungling the planet would get rid of vital food sources for humans and wildlife. Which would get rid of MORE vital food sources from the humans. $\endgroup$ – Synergetic May 31 '17 at 14:56
  • $\begingroup$ @Xynozore The climate will mess with the diseases by removing their ideal environment, reducing there effectiveness when humans start landing. No colony ship worthy of the name would go somewhere without a lot of stored food and enough seeds to cultivate all their food needs three times over (new planet, your first harvest is probably going to fail) $\endgroup$ – Overthinks May 31 '17 at 15:30
  • $\begingroup$ Right, makes sense $\endgroup$ – Synergetic May 31 '17 at 15:59

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