Show HN: A self-running space economy SIM in Rust and Bevy

github.com

57 points by kalcode 3 hours ago


I built this with Claude cause I always wanted to tinker with a simulation economoy and I love space themes.

A space-economy sim where nothing is scripted. A few hundred autonomous ships each run their own planner. Some chase the best trade route, take a delivery contract, refuel, retrofit at a shipyard, or dock so the crew can rest before morale tanks.

Markets price everything off supply with shortage-urgency multipliers, factions tax and subsidize, populations migrate when they're unhappy, and stations that go broke get abandoned and rot.

It started as an Elixir/Phoenix prototype, but the BEAM scheduler struggled on Windows gaming PCs, so I had Claude rewrite the engine in Rust.

The sim core is pure, synchronous, IO-free (its own hecs ECS), and the Bevy client embeds it directly as a library, sim and renderer share one world with zero marshalling. Ship AI is a GOAP planner over a world state; ships replan mid-flight when a better option appears. ~485 agents today at p50 ~10-20ms/tick, architected to push toward 100k+. Single native binary, bundled SQLite, no runtime deps. Getting into 100k has been a struggle, but I have pushed it into the thousand and it was running fine.

It's a sandbox, not a game yet, there's no objective yet, and I'm not actively pushing it toward "shippable." Anyone can fork it and take it over. Or it can stay as some type of AI slop, but part of me thinks it is already in a pretty good shape for a simulation use for various games or ideas.

(Full disclosure: a lot of this was built pairing with Claude. That's how I had the bandwidth to take it this far. Happy to talk about what that workflow actually looked like.)

awhitty - 18 minutes ago

This is awesome. I've been working on a similar concept based on the Escape Velocity series and love the space trader genre in general. I'm curious how you've thought about the faction organization structures as well as information flows in the sim? Are agents omniscient about prices and postings? I ended up making in-sim information a commodity that agents could choose to sell to each other, but I didn't follow through fully baking that dynamic.

lantry - 36 minutes ago

I have also been using LLMs (mostly claude code) to develop a game with Rust and Bevy, and it seems to work very well. The strictness of rust seems to really help them get the code right, and the ECS architecture seems to make it easy for them to reason about how things work (because they only need to hold a few systems and components in context at a time).

makes me wonder if ECS will ever catch on outside the gaming industry. not sure if it's really the right architecture for web SAAS. Might be interesting to rewrite some big piece of software with ECS.

dangoodmanUT - 2 hours ago

throws away spec doc for my own

Are we all having this idea?

qwertyastronaut - 2 hours ago

What is it about the space industry life that makes us developers adore it so much? :p

X4 Foundations just got a big update if you’re looking for a game built around this industry sandbox idea.

sulam - 3 hours ago

It’s fun to see projects like this that seem largely unlocked by LLM assistance, and probably wouldn’t even get started if it weren’t for them. I know the hype cycle for LLMs seems to have hit its peak already, but I am fully convinced we are still in the early days of what we’ll be doing with them in software development. The only problem I see with projects like this is that there could be so many of them. Personally I’ve built at least 5 things that I had thought would be fun, but realistically I just didn’t have the time. Now I do, and if they only scratch my personal itches, that’s okay.

hersko - 3 hours ago

Neat idea!

I think it would be cool if you can host a simulation and enable online viewers. Have the simulation accessible from a website (god-mode disabled of course), and have an agent generate some sort of newspaper or news bulletin of interesting things that happen.

digilypse - an hour ago

I just started working on some similar stuff, it’s been a dream forever but I never had time for the payoff to feel worthwhile. Would love to hear more about your Claude workflow and experience with Bevy, did you consider Godot?

nixpulvis - an hour ago

Not using big_space :(

thomascountz - 2 hours ago

Reminds me of SpaceTraders[1]

[1]: https://spacetraders.io/

spacecadet - an hour ago

You might also like my AI written zero player game/sim: https://github.com/derekburgess/simcraft

The whole thing originated years ago to see what LLMs were capable of. Just spent a chunk of my Fable access hacking away at it. Is it intended to be 100% realistic, no. Its more art, tho I do try to lean into physics...