A promptable simulator that learned physics.
A world model is a neural network that learned to predict what happens next. This one is promptable: pick a world, or type one, and the same network simulates its physics. It runs its whole loop on your device (your action and the world you chose go in, it paints the next frame, feeds that back, and paints the one after) a playable world with no physics engine behind it, just a network that learned the rules by watching. Drive it below.
Watch, dream, drive.
The frontier of embodied AI is learning to imagine consequences. This is that idea, shrunk until it fits on your device and you can hold it.
Learned the physics from pixels
Trained only on rendered rollouts across six worlds, never told the rules. Momentum, friction, the bounce off a wall, an ambient pull of gravity or wind: all inferred from watching frames.
One network, many worlds
Pick a world (moon, ice, mud, downhill, wind, arena) or type one, and an environment code selects it. The same weights simulate whichever physics you ask for. A prompt chooses the world, the Genie and Oasis idea at nano scale.
The network is the engine
At run time there is no simulator. The last two frames, your action, and the world code go in; the network paints the next frame, then that becomes the input for the one after, playable, in plain JavaScript, no server and no cloud.
Small, and measured.
Evaluated on held-out rollouts it never trained on.
It is deliberately tiny, and it is an approximation, not a perfect simulator: over a long unbroken run the network can let the rover soften or drift, because it is guessing every pixel from what it learned rather than solving equations. That honesty is the point. The frontier versions of this idea, playable neural game worlds generated frame by frame, are hundreds of millions of parameters and need a GPU; this one shows the same <i>idea</i> at a scale you can hold, released and runnable, on the device in front of you.
In the field, and worth being honest about: this model is generative, it predicts every pixel. A second school argues that is the wrong target for physical AI. A Joint-Embedding Predictive Architecture (JEPA, LeCun) predicts in a learned latent space instead, so it can ignore unpredictable surface detail and keep only the structure that supports planning, the line runs from I-JEPA through V-JEPA 2 (zero-shot robot manipulation) to VL-JEPA. Its mathematical basis is the energy-based model, the same frame Logical Intelligence's Kona uses for reasoning: score every candidate by an energy and descend to the lowest valley, rather than sampling the most likely token. Predicting pixels is the most legible way to hold a world model in your hand, which is why this one does; predicting latents may be the way it scales. Both are world models, and the Institute is building toward both.
Weights and the recipe.
nano-world-model-multi
The promptable weights, config (worlds, tints, aliases), and a runnable example. One network, six worlds, trained with a multi-step rollout loss to stay stable when it drives itself.
Vision-language-action
The released VLA policies (a tiny open-vocab arm, multi-step manipulation, the real 450M SmolVLA) all runnable on-device.
World Models
The course on how a learned simulator like this one is built, from next-state prediction to a playable world you plan in.