Making a Game on a Custom Bytecode Vm in 7 Days and 3kb
Key topics
Diving into the fascinating world of minimalist game development, a developer recently created a game on a custom bytecode VM in just 7 days and 3kB, sparking a lively discussion about the project's technical wizardry and the joys of simplicity. Commenters marveled at the retro aesthetic, with some likening it to a late 80s passive matrix color LCD screen, while others praised the productivity achieved in such a short timeframe. The conversation also touched on related game jams, including one that attracted over 200 participants, and the delight of seeing developers push against the trend of bloated, LLM-driven projects. As commenters explored the project's context, they drew parallels with other creative coding challenges, such as js13kgames.
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Dec 19, 2025 at 8:00 AM EST
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Anyhow, I think if this was my forum I would put the downvote selector at the end of the comment title and have the upvote selector at the beginning.
The source code is here: https://github.com/laurentlb/shmup8/blob/main/src/shaders/sc...
Blending is on lines 241, 242.
I didn't try to get a specific 80s look, I just played with formulas.
https://itch.io/jam/langjamgamejam/entries
We plan on running it again: https://langjamgamejam.com/
Cheff kiss!
- Designed a language.
- Implemented a compiler to compile it to bytecode, using F#.
- Wrote a bytecode interpreter, using C++.
- Created a shoot’em up game, using the custom language.
- Renderd the graphics, using a single GLSL shader.
Claude called the language Blitz.
The repo it created: https://github.com/fragmede/blitz
Is the code shit? I haven't looked at it. Didn't have to. I fed it the blog post at the end, and difference.md has a comparison on what Laurent Le Brun built vs Claude, and Claude is fully aware that it went a different way on a number of different things.
It chose python.
I had to tell it to use uv.
I'm on a mac with high DPI and it got confused about that.
I had to tell it to make a binary format (it called it BLTZ)
But you can clone that repo, do uv run main.py --compile game/shooter.blitz and it'll make a .blitzc. Then you can do uv run main.py game/shooter.blitzc Tear the code apart. Call out every tiny mistake in that repo. It's probably cheating somewhere! But all I did was give it challenge.png that's in the repo, and very little English, and Claude went to work.
It's been 21 years since my college computer graphics class and I went into distributed systems and not game dev, so someone else will have to tell me if it used a single (or even any!) GLSL shaders or not.
Call it slop all you want, but that took me 70 minutes of babysitting.
None of this is individually difficult, but an actual human being had the motivation and talent to bring it all together in 7 days, which is impressive.
So what if an LLM can create the same components if you tell it to. It's a bit like someone sharing a handknit sweater they just made, and you counter with "Well, here's a machine made one I bought in Walmart, made in 5 min in China".
The difference is the baseline. Once the default outcome is cheap, fast, and good enough, the human effort stops standing out in a way that matters. At that point, pointing at the Walmart sweater is not missing the point, it is the point.
Should people stop playing chess just because a free chess engine can trounce everyone on the planet?
Humans can be awesome. Machines are just machines.
What you're describing is 7 days of productivity supported by probably 7+ years (or 27+ years) of experience and learning and getting things wrong and restarting over again.
It is definitely wonderful to see though.
https://en.wikipedia.org/wiki/CHIP-8
and
https://en.wikipedia.org/wiki/SWEET16
It seems so un-FORTRAN that DEC had a FORTRAN compiler for the PDP-11. that was based on a stack machine and then later built an FP accelerator specialized to accelerate the stack machine. It was a straggler but I'm still trying to track down a circa 1992 article from Dr. Dobb's Journal where someone used virtual machine techniques to unbreak the broken i860 and make a good FORTRAN compiler.