I have a fairly-straightforward alternate modern-day Earth setting, somewhat similar to Ace Combat's Strangereal or the 'America' seen in Rockstar North's GTA series (real life, with the serial numbers filed off).

I'd like to take my counterpart countries etc and place them on a map that's reminiscent of Earth - similar proportions of water to land, ice to forest, etc - but which doesn't reflect the continental or country layout of our home planet.

It would be nice to accommodate (even coarsely) procedures like erosion, rain shadows, tectonic plate movement, etc in the production of this world / worldmap, but unfortunately I am no geologist / tectonic engineer.

It's a somewhat grandiose question, but... Is there a means to automate the process of building a mostly-accurate new planet? Can you recommend a piece of software, a web app or a guide I can follow to construct my globe?

This kinda imaginative exercise is quite new to me - any suggestions would be appreciated! Thank you!


Google maps.

the place

Mountains. Forests. The confluence of two great rivers. It is on our Earth now. Recognize it? If so, answer in ROT18 please in comments.

There are features on earth now that are real, but are not easy to recognize out of context. You can copy all of their landforms intact, down to placement of cities. And it will all be correct according to plate tectonics, erosion, etc.

If out of principle you do not want to use Google maps, you can still use Earth.

earth, cretaceous


It is Earth in the Cretaceous. This site will take you back as far as you like but there are other that will take you forward, shifting the continents to unrecognizability. Again, no-one will be able to say you made up something stupid or ignorant. Or if they do you can point at God and say "You talking to Him?"

Comment noted: you want random and unique. How about this?

fractal world


You give it parameters (%water, %ice, iteration) and a random number seed and it makes you a world. I think Minecraft uses something similar.

  • $\begingroup$ Hi Willk! Thanks for the answer! While I agree w/you that usually 'starting with Earth' is a good idea for fiction (indeed, I've used this: flipping UK around to invent new island) & that you can't really argue with established physical processes, I'm still leaning towards generating something afresh. Namechecking 'rain shadows' may've indicated a degree of detail that I'm not really looking for- I'm happy kitbashing geography at that scale. The DinoPics link is awesome, & it's the world at the scale I'd like to hit, but I'd like to try for something unique. But these are amazing fallbacks! $\endgroup$ – Reverend Speed May 30 '20 at 17:24
  • $\begingroup$ Thank you for your patience and flexibility! I'm only starting out with this thing, so your kind advice is much appreciated. =D I'll experiment with the donjon generator. Definitely seems like a level of complexity that would work well with Minecraft. Cheers! $\endgroup$ – Reverend Speed May 31 '20 at 18:26

If you are genuinely concerned about tectonics, the only simulation tool I'm aware of is this.

Otherwise, I'm a fan of Azgaar's FMG, although it's a bit better suited to smaller-scale stuff (islands, small continents) rather than full worlds. The climate simulation seems decent, but the way it generates heightmaps isn't particularly based on real processes.

One issue I think you're going to have is that I don't know of anything that does world-scale generation down to the degree of detail where erosion is going to matter significantly. You're asking about processes that occur at very different scales.

  • $\begingroup$ Holyshit tectonics.js is IMPRESSIVE. It's interesting he namechecks Alan Zucconi's work- but the underlying code is far beyond my paygrade as a c# dev. I might try to dig into this- though I'd like to be able to turn off the light sim to better inspect the landmasses... & export the entire file or heightmaps as an .obj or something... Azgaar's FMG is certainly a very cool app (& while the heightmaps are arbitrary, it's great to be able to export something I can use in 3D). Regards detail (eg. erosion), I think you're right, going to have to cover for that in the narrative framing. Thank you! $\endgroup$ – Reverend Speed May 31 '20 at 18:35

The Youtube channel Artifexian does a lot of good videos about building planets from scratch, but I'm afraid he doesn't have a lot of good words to say about any of the programmes that artificially generate geographic features. I guess it comes down to where you want the balance between being quick-and-easy (in which case, the map generated above is perfectly sufficient), or being as scientifically plausible as possible.

  • $\begingroup$ Hey Tom, thanks! Artifexian is a great call - Edgar and Bill do incredible work. At the moment, I guess I'm going to 1) aim for quick-and-easy, 2) cover for my laziness by leaning on unreliable narrators (for internal political reasons or just ignorance, see en.wikipedia.org/wiki/Mercator_projection ), 3) course-correct on further iterations, covered by the unreliable narrator. I always admired Pratchett's approach of not making maps until there was some 'there' there, but I'm sort of using this map to organise my current ideas (& jumpstart others), so it should be fine. Thanks again! $\endgroup$ – Reverend Speed May 31 '20 at 18:44

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