OpenCode + LLM to create a 1:1 Settlers of Catan clone. Guess which model I did it with!

Posted by maxwell321@reddit | LocalLLaMA | View on Reddit | 36 comments

Hey all!

I've been waiting to make this post until I was completely done with the game so I can have a live preview, but this weekend is going to be pretty busy for me and I'm getting antsy to share what I've been working on with you!

I've been working on a 1:1 recreation of my favorite board game, Settlers of Catan. I challenged myself to do this with OpenCode and a local AI model.

I'm lucky to have an AI machine with two 2 RTX 3090's (used to be 3, RIP the last card), 1 P40, and 128GB of DDR4 memory. For the longest time I've played with local models and used them for day to day tasks, but never had much luck vibe coding with them and getting quality results that were worth the hassle.

Over the last few months though, this changed. Below I have listed five models that I've ran on my machine and successfully done some vibe coding with via OpenCode, and I used ONLY ONE OF THEM to create this 1:1 recreation of Settlers of Catan, all in just two days. The only work it didn't do was downloading and/or scanning the real life textures of the tiles.

The game is completely functional, it has multiplayer functionality via "rooms"' and is the full experience. Chat, trading, special conditions like Longest Road and Largest Army, all are there! The only inaccuracy I know of so far is the ability to see other's exact hands. Typically in a Catan game people keep their hands private.

So, as I mentioned. I used exactly ONE model with opencode for this project. The only thing I provided the model with was a PDF of the game manual (converted to text) and also the official Catan Q&A. I believe it asked a question or two during the planning phase, but I genuinely didn't give it much to work with. I was really surprised to see how well it understood the logic, even the nitty gritty rules.

I would like you guys to guess which model I used, and I'll reveal it sometime next week alongside the live demo of the game.

Here are your choices:

Qwen 3.6 27B - Q8

Gemma 4 31B - Q8

Qwen 3.5 122B - Q8

GPT OSS 120B - Q8

MiniMax M2.7 229B - UD Q4_K

Comment what model you think did it! Also feel free to ask any questions.

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maxwell321@reddit (OP)

The only reason it's delayed is because I need to replace the textures with royalty free stuff. It turns out that the game concept itself isn't copyright, but the textures are.

My clone is for educational purposes but I still want to honor their copyright and only release it when I'm completely free of the Catan assets.

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chipotlemayo_@reddit

!remindme 2 months

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maxwell321@reddit (OP)

It probably would if this were going to be a publicly released project, which is why before I have the live demo I'm going to replace them

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maxwell321@reddit (OP)

No idea, it still seems to show for me. Local mods may have removed it? Idk

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maxwell321@reddit (OP)

In my opinion, not really. Anyone who plays the real life game can pay attention to the rolls and know anyone's exact hand, it's not really fundamental to winning but it surely does help.

There are so many other niche things it nailed, notably these factors I'm suprised it got:

During the first setup phase, people placing the first set of settlements in a random order, and then for the second set of settlements it's the reverse of that order, AND getting your initial resources ONLY from the second settlement tiles

Only allowing development cards to be played the NEXT turn after creating one, limiting to one per turn

Hodler-mane@reddit

27b. choice of 3090 users

alphapussycat@reddit

Yeah, just unfortunate highest that fits in 24gb is q5.

32gb cards would be perfect for 27b, could even do q8.

TripleSecretSquirrel@reddit

I have a 32gb card and use UD_q4_k_xl. I've seen a solid handful of benchmarks that seem to show that q4 has no meaningful degradation from q8, and the ability to fill a full context window is important for coding. Anecdotally, my q4 model is really solid.

If I used the unsloth Q8_0, I'd have like a single gigabyte available for KV cache.

I tried it on split ram/vram, super slow, but just to test how accurate it is. qwen3.5 27b q4 would write a similar unity function name, where it used an almost synonym to the real function name.

So at q4 it's definitely degraded, quite noticeably. 9b at higher quant does not make that mistake.

CoolestSlave@reddit

Also the low t/s count on q8.

Euphoric_Emotion5397@reddit

qwen 3.6 35B MOE model! 😄

hideo_kuze_@reddit

!remindme 1 week

hitpopking@reddit

Accomplished_Ad9530@reddit

Also feel free to ask any questions.

Which model did you use?

cristianlukas@reddit

Amazing! Do you plan o opening the source code? I want to make a derivative game based on Catan but with Patagonian tribes and different biomes and things based on real Patagonian myths, and your base could be a good starting point (I already made the rules and artwork of everything)

edsonmedina@reddit

I'm sure it's not Gemma. The tool calling is a disaster so it would take forever.

Potential-Gold5298@reddit

I'm betting on the Gemma 4 31B. The Qwen3.6 27B won't surprise anyone, just like the Qwen3.5 122B-A10B. The MiniMax is even less so. I'd be most surprised if it were the gpt-oss-120B.

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LadyPopsickle@reddit

Off topic question - Isn’t it illegal or authorship/ownership infringement to scan cards and usem them as your own assets?

I mean unless you start raking in serious money noone will care. Just curious.

OP's post now says "[removed]". What gives?

My guess is 27B

But I'd be interested in knowing how long it took to generate all that code?

Joly0@reddit

Other question is, will you release the source code?

Valuable-Site9454@reddit

The only inaccuracy I know of so far is the ability to see other's exact hands.

That's a pretty big "inaccuracy".