I built a Darwinian simulator where AI agents can die, reproduce and compete for survival.
Inspired by
@karpathy's nanochat, I called it
>nanolife
(find in repo: nanothrones, nanomatrix, nanorings, etc)
Runs are cheap enough to treat as experiments: $0.50–$2 on Groq. Up to a $5 on frontier models, depending on ticks and population.
It's a minimalist implementation, built on just 7 primitives: scarcity, reputation, environmental harshness, heredity, memory compression, local observation, world log.
Unlike heavier multi-agent stacks with orchestration frameworks, retrieval, and embeddings, nanolife is a minimal harness for LLM-driven artificial life and social simulation in a small, readable codebase.
You set API keys, run one module, and watch dozens of agents tick in parallel in the terminal. When the run ends you get charts, a social graph, and an LLM-written academic report.
The core loop is on the order of ~350 lines in
engine.py and is built to stay hackable:
- Parallel cognition loop (observe, act, log, resource drain, births/deaths, log compression)
- Maslow hierarchy in the prompt
- Lamarck-inspired inheritance to offspring
- Postmortem pipeline
- Runs on Groq by default or OpenRouter
- Benchmarking models is possible
- Modular: you can swap CognitiveFunction, CompressionFunction, SpreadFunction, or Scenario without rewriting the engine
Excited to release new repo: nanochat!
(it's among the most unhinged I've written).
Unlike my earlier similar repo nanoGPT which only covered pretraining, nanochat is a minimal, from scratch, full-stack training/inference pipeline of a simple ChatGPT clone in a single, dependency-minimal codebase. You boot up a cloud GPU box, run a single script and in as little as 4 hours later you can talk to your own LLM in a ChatGPT-like web UI.
It weighs ~8,000 lines of imo quite clean code to:
- Train the tokenizer using a new Rust implementation
- Pretrain a Transformer LLM on FineWeb, evaluate CORE score across a number of metrics
- Midtrain on user-assistant conversations from SmolTalk, multiple choice questions, tool use.
- SFT, evaluate the chat model on world knowledge multiple choice (ARC-E/C, MMLU), math (GSM8K), code (HumanEval)
- RL the model optionally on GSM8K with "GRPO"
- Efficient inference the model in an Engine with KV cache, simple prefill/decode, tool use (Python interpreter in a lightweight sandbox), talk to it over CLI or ChatGPT-like WebUI.
- Write a single markdown report card, summarizing and gamifying the whole thing.
Even for as low as ~$100 in cost (~4 hours on an 8XH100 node), you can train a little ChatGPT clone that you can kind of talk to, and which can write stories/poems, answer simple questions. About ~12 hours surpasses GPT-2 CORE metric. As you further scale up towards ~$1000 (~41.6 hours of training), it quickly becomes a lot more coherent and can solve simple math/code problems and take multiple choice tests. E.g. a depth 30 model trained for 24 hours (this is about equal to FLOPs of GPT-3 Small 125M and 1/1000th of GPT-3) gets into 40s on MMLU and 70s on ARC-Easy, 20s on GSM8K, etc.
My goal is to get the full "strong baseline" stack into one cohesive, minimal, readable, hackable, maximally forkable repo. nanochat will be the capstone project of LLM101n (which is still being developed). I think it also has potential to grow into a research harness, or a benchmark, similar to nanoGPT before it. It is by no means finished, tuned or optimized (actually I think there's likely quite a bit of low-hanging fruit), but I think it's at a place where the overall skeleton is ok enough that it can go up on GitHub where all the parts of it can be improved.
Link to repo and a detailed walkthrough of the nanochat speedrun is in the reply.