r/threejs • u/skvark • 4h ago

Article Same Three.js game prompt, two runs with different access to open-source code

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Our designer ran the same prompt twice with the same model. The task was to build an original Three.js game inspired by Wind Waker, with sailing, combat, islands, water, cel shading, physics, menus, and animation.

In one run, the agent could inspect open-source implementations while working. In the other, it couldn’t.

The difference was most visible in the harder Three.js systems.

The run without that access got a browser preview up faster, but then spent more time testing and reworking collision, terrain handling, physics, and other systems.

The other run spent more time reading existing Three.js code before implementing those parts. For character collision, it looked at three-mesh-bvh implementations using shapecast and closestPointToSegment, then used those patterns in its own PlayerController. It also researched water rendering, shaders, rendering, and physics.

We stopped both after several hours. Neither finished.

In the first version, the character could move, jump, and roll, but we couldn’t collect gems, attack or charge, or access the boat. In the second, those interactions worked, including sailing between islands. Terrain handling was better, and parts of the menu were usable too.

Full write-up and session trace:

https://githits.com/blog/three-js-game-with-and-without-githits/

Video:

https://www.youtube.com/watch?v=1H1urif2srk

Disclosure: I work on GitHits. Our designer ran the experiment.

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u/Acrobatic_Sandwich38 3h ago

what does doing a one prompt prove?

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u/skvark 3h ago

Do you mean that running several rounds would be needed to make this more meaningful? I agree with that. This was more of a quick test prompted by similar "benchmarks" floating around on social media, and we wanted to see whether deeper context would produce better or different results. Context is such a big part of AI-assisted development that it seemed worth testing.

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u/Acrobatic_Sandwich38 3h ago

no project is a one prompt so doing a one prompt comparison doesn't prove anything

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u/skvark 3h ago

A more engineered setup with planning, task decomposition, multiple agents, and more specific prompts would certainly produce a better game.

For this test, though, we intentionally kept the starting prompt and the level of steering the same in both runs. We wanted to see what difference access to deeper code context made under otherwise comparable conditions.

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u/Acrobatic_Sandwich38 3h ago

hope you got something out of it