Astropolis is a simulation game that explores human expansion and evolution in our own solar system. It is an early-stage, open-development project created by Charlie Whitfield (that’s me!) in the I, Voyager solar system simulator using the Godot Engine.

What is Astropolis about?

It is the story of becoming a Kardashev Type II civilization1 in two installments. In the first, we’ll see off-Earth mining and manufacturing, interplanetary economies, O’Neill cylinders and other space habitations, and humanity on its way to becoming multiplanetary (or non-planetary). And in the second: artificial general intelligences, virtual and other kinds of humans, terraforming, planet harvesting, star lifting, and a realistic Dyson swarm. These lists are only possibilities, however, as civilization may evolve in different directions. The two installments are presently code-named “Outward Bound” (borrowed from Isaac Arthur) and “K2.”

A diagram of the solar system from Galileo Galilei's Dialogus Systema Mundi, 1635.
Galileo Galilei’s diagram of the solar system from Dialogus Systema Mundi, 1635

In Astropolis, you will start as a single organization, most likely a public space agency or private space company. If your organization splits or gives rise to a new entity over time, you’ll have the opportunity to become this new branch of humanity: perhaps a newly independent Mars colony, or something quite different and not-exactly human. Alternatively, we’ll have a sandbox mode that let’s you build as any faction without financial or material constraints. There are no victory conditions per se, but there are many possible achievements involving population, economy, energy (i.e., the Kardashev scale), manufacturing, constructions, computation, information, biomass and biodiversity. You are free to pursue either competitive or cooperative approaches. However, many achievements are about whole solar system metrics.

“Space is big. Really big.”2 Our solar system can support more humans than appear in most sci-fi representations of whole galaxies — quadrillions, easily, considering only the biological kind. What does such a civilization look like? That’s the question I’m asking in Astropolis. Reality gives us interesting game challenges, the Rocket Equation being the foremost from an economics point of view (don’t worry, we’re not designing rockets!). Similarly, speed-of-light communication sets our game scope. Although settlement of other star systems will be possible in K2, near-real-time active engagement is possible only in one star system at any time.

1 A Kardashev Type II civilization consumes energy similar to the Sun’s total luminosity, about 3.8 x 1026 W. Or, in Carl Sagan’s extended scale, Type 2 is defined at 1026 W. The Kardashev scale is only one of many ways to measure your progress in Astropolis.

2 “…You just won’t believe how vastly hugely mind-bogglingly big it is.” Attribution to Douglas Adams, who understood the value of a footnote.

Is Astropolis moddable?

Absolutely! This is a priority. All of Astropolis’ content data and a large part of its code (including all GUI and AI) is exposed and moddable. This part is maintained in an SDK (software development kit) in a public GitHub repository. Simple text tables define all game content, which means you can mod entirely different solar systems, different players, different resources, different industrial processes, or virtually anything else. I’m especially excited to open up the AI code. Let’s face it, game AIs are still largely terrible at the grand and strategic levels. (Please inform me if you know any exceptions!) I think we can do better. By exposing the AI code, I’m enabling you, the fans and modders, to push me where direction might be needed, or to do it better yourself if you like.

What is the current state of development? When will it be released?

I’ve already released our first development build! However, Astropolis is very early in its development. The underlying solar system model (I, Voyager) is quite advanced. Resource, manufacturing, economic, technological, political, social and cultural models are at different stages, some near completion and others still on the drawing board. Realistically, official release of the first installment, Outward Bound, is several years in the future. My hope for 2023 and 2024 is to build the simulation. From there I anticipate a year or more of work to go from simulation (which may feel a bit sterile) to an immersive game experience.

What do I mean by “open development”?

I’m sharing the development process via dev blogs at, a discussion forum, a public view of our moddable code repository, and periodic development builds. The dev builds will remain free as long as we are in the “simulation building phase,” which will be for a while yet. To be clear, Astropolis is NOT open source. It’ll be a game for sale when it is ready. However, you are invited to participate in the development process and help me make Astropolis an awesome game.

What is the relationship between Astropolis and I, Voyager?

I, Voyager is our solar system model. It is a free, open-source development platform, itself built on the free, open-source Godot Engine. My intention is for I, Voyager to become a community project over time (do you want to help with that?). Astropolis is a for-profit game that I am building on the I, Voyager platform. Well, that’s the technical explanation. The truth of the matter is that Astropolis has always been the goal and I, Voyager is my “half-way there” milestone. This is a marathon effort!

What kind of art/graphics will Astropolis have?

I’ll be hiring artists very late in development. In the meantime, expect some interesting “emergent art” and shader work (i.e., GPU programming) from me. Our site’s header image is one example! (What is that, anyway?) See also my Saturn Rings shader. As a general rule, expect to see procedural visuals in addition to fixed art assets. Ultimately, our Dyson swarm will be a shader effect that resolves to individual objects as you zoom in. And long before that, we’ll see strategic views with tens of thousands of freighters in their Hohmann transfer orbits. If these sorts of things excite your imagination, then this is a game for you!

What’s coming in the dev blog?

I’ll delve more deeply into specific areas of Astropolis. I’m thinking roughly every other month at the start, picking up in frequency much later in development. Some likely topics:

  • The Resource Model. How do I account for all of the iron in the solar system? What is the right level of resource abstraction?
  • The Economics Model. Is this the Austrian School, or what? Futures contracts: An overcomplication? Or a simplification for you and the game AI? Have you seen the price of Bitcoin lately?
  • The Science, Technological and Engineering Models. How can I be “realistic” in some way and still surprising (which is, to be fair, realistic) about future advancement? 
  • The Biological Model. How much biomass can the solar system support? How do I model biodiversity? Are humans evolving and what might they evolve into? Do we need biology at all?
  • Evolution, broadly speaking. Does evolution have a direction? How does population size and structure affect evolution? How do I model other, non-biological, kinds of evolution: technological, political, economic, social and cultural?
  • Program architecture. OOP or data-centric, or a bit of both? How am I fencing off the game AI, GUI, and you the modder from internals? And how does this relate to design for multithreading and multiplayer?
  • Progress reports, from time to time.
  • And whatever else I feel like… Post-scarcity societies? The Fermi Paradox? Who knows?

How can you help?

Please spread the news and say hi on our Forum! We’re also on Twitter @t2civ and Facebook /t2civ. It’s quite a road ahead and I can use some encouragement!