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My 2.5 year old laptop can write Space Invaders in JavaScript now (GLM-4.5 Air)

(simonwillison.net)
577 points simonw | 4 comments | 29 Jul 25 13:45 UTC | HN request time: 1.009s | source
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stpedgwdgfhgdd ◴[29 Jul 25 14:30 UTC] No.44723879[source]▶
Aside that space invaders from scratch is not representative for real engineering, it will be interesting to see what the business model for Anthropic will be if I can run a solid code generation model on my local machine (no usage tier per hour or week), let’s say, one year from now. At $200 per month for 2 years I can buy a decent Mx with 64GB (or perhaps even 128GB taking residual value into account)
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falcor84 ◴[29 Jul 25 15:04 UTC] No.44724300[source]▶
How come it's "not representative for real engineering"? Other than copy-pasting existing code (which is not what an LLM does), I don't see how you can create a space invaders game without applying "engineering".
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phkahler ◴[29 Jul 25 15:15 UTC] No.44724424[source]▶
>> Other than copy-pasting existing code (which is not what an LLM does)

I'd like to see someone try to prove this. How many space invaders projects exist on the internet? I'd be hard to compare model "generated" code to everything out there looking for plagiarism, but I bet there are lots of snippets pulled in. These things are NOT smart, they are huge and articulate information repositories.

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simonw ◴[29 Jul 25 15:16 UTC] No.44724436[source]▶
Go for it. https://www.google.com/search?client=firefox-b-1-d&q=github+... has a bunch of results. Here's the source code GLM-4.5 Air spat out for me on my laptop: https://github.com/simonw/tools/blob/main/space-invaders-GLM...

Based on my mental model of how these things work I'll be genuinely surprised if you can find even a few lines of code duplicated from one of those projects into the code that GLM-4.5 wrote for me.

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phkahler ◴[29 Jul 25 15:34 UTC] No.44724682[source]▶
So I scanned the beginning of the generated code, picked line 83:

  animation: glow 2s ease-in-out infinite;
stuffed it verbatim into google and found a stack overflow discussion that contained this:

      animation: glow .5s infinite alternate;
in under one minute. Then I found this page of CSS effects:

https://alvarotrigo.com/blog/animated-backgrounds-css/

Another page has examples and contains:

  animation: float 15s infinite ease-in-out;
There is just too much internet to scan for an exact match or a match of larger size.
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1. simonw ◴[29 Jul 25 15:39 UTC] No.44724749[source]▶
That's not an example of copying from an existing Space Invaders implementation. That's an LLM using a CSS animation pattern - one that it's seen thousands (probably millions) of times in the training data.

That's what I expect these things to do: they break down Space Invaders into the components they need to build, then mix and match thousands of different coding patterns (like "animation: glow 2s ease-in-out infinite;") to implement different aspects of that game.

You can see that in the "reasoning" trace here: https://gist.github.com/simonw/9f515c8e32fb791549aeb88304550... - "I'll use a modern design with smooth animations, particle effects, and a retro-futuristic aesthetic."

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2. threeducks ◴[29 Jul 25 16:49 UTC] No.44725637[source]▶
I think LLMs are adapting higher level concepts. For example, the following JavaScript code generated by GLM (https://github.com/simonw/tools/blob/9e04fd9895fae1aa9ac78b8...) is clearly inspired by this C++ code (https://github.com/portapack-mayhem/mayhem-firmware/blob/28e...), but it is not an exact copy.
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3. simonw ◴[29 Jul 25 16:53 UTC] No.44725675[source]▶
This is a really good spot.

That code certainly looks similar, but I have trouble imagining how else you would implement very basic collision detection between a projectile and a player object in a game of this nature.

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4. threeducks ◴[29 Jul 25 17:32 UTC] No.44726128{3}[source]▶
A human would likely have refactored the two collision checks between bullet/enemy and enemyBullet/player in the JavaScript code into its own function, perhaps something like "areRectanglesOverlapping". The C++ code only does one collision check like that, so it has not been refactored there, but as a human, I certainly would not want to write that twice.

More importantly, it is not just the collision check that is similar. Almost the entire sequence of operations is identical on a higher level:

    1. enemyBullet/player collision check
    2. same comment "// Player hit!" (this is how I found the code)
    3. remove enemy bullet from array
    4. decrement lives
    5. update lives UI
    6. (createParticle only exists in JS code)
    7. if lives are <= 0, gameOver