5 ms·

A whole boss fight in 256 bytes

130 points by HellMood 6mo ago

HellMood 6mo ago
Technical write up for "Endbot" 256 bytes MSDOS program with plot, sync, sound, and payoff. Released April 4th at Revision Demoparty 2026.
ale42 6mo ago
Didn't run it (yet) but it looks nice. Great that some people are still able to optimize code! I'm wondering if this would run on actual hardware (VGA + a sound card supporting MPU401 emulation)
- bitwize 6mo ago
  We're gonna find that Claude Mythos can do something like this in 255 bytes
  - HellMood 6mo ago
    I mean now that the (human written) source for this is out in the wild, of course it can ;)
  - streetfighter64 6mo ago
    Optimizing away one byte of this, given the source code? Yeah, could happen. Making a good 256 byte demo from scratch? No way.
    - HellMood 6mo ago
      I mean, give it a try? the source is right there ;)
- HellMood 6mo ago
  I ran a patched version of it on WinXP (DOS NTVDM), the sound works there! But it requires a few extra bytes to enable MIDI UART Mode first. On DosBox-X, this can simply be set in the config ;)
lucb1e 6mo ago
That domain is such a blast from the past for me. I spent so many hours working on projects with free webhosting as a teen! dang/HN: this domain should probably be added to the list where the subdomain is shown next to the title, since subdomains are users' webspaces. (Might be a good candidate for the public suffix list: "[DNS labels] under which Internet users can (or historically could) directly register names".)
flopsamjetsam 6mo ago
I clicked on this fearing it was a "256 bytes of JS" (plus X GB of browser), and was pleasantly surprised it was actually 256 bytes.
- rustystump 6mo ago
  Why is that bad? If the bytes could easily run within the same constraint in another env/language why the hate? I am with u on the excessive ram of browsers. It is insane. Still, it is one of the most portal and easy ways to share something. Heck, u can run a dos emulator in your browser.
  - senfiaj 6mo ago
    Probably because JS has larger runtime, in JS you don't have to write about most of the low level code. So it's easier to squeeze code in JS than in ASM or machine code.
  - layer8 6mo ago
    This is probably in reference to things like Dwitter.net (https://news.ycombinator.com/item?id=46557489 https://news.ycombinator.com/item?id=46557489), where the browser (plus the Dwittet-specific runtime harness) contributes significantly higher-level functions than traditional demoscene targets like DOS PCs. It’s just a different thing. I see no “hate”, only an expression of preference for “bare-metal” demos.
    - selcuka 6mo ago
      Here's a 13-byte demo that runs on Chrome browsers: chrome://dino
  - irishcoffee 6mo ago
    It is misleading to say "I wrote X in 1k bytes" when those 1k bytes were library calls to library calls totaling 300MB.
    - 6mo ago
Anmol-Baranwal 6mo ago
[dead]
philxor 6mo ago
And it came in 5th place in the competition. The winner was this one which is 16 bytes... https://www.youtube.com/watch?v=QKLhH_ANwIc https://www.youtube.com/watch?v=QKLhH_ANwIc
- omoikane 6mo ago
  Writeup: https://www.reddit.com/r/tinycode/comments/1se0iyt/writeup_for_16_byte_intro_rainbow_surf_1st_place/ https://www.reddit.com/r/tinycode/comments/1se0iyt/writeup_f...
- HellMood 6mo ago
  The demoscene has a curated collection of "best 16 bytes ever" https://nanogems.demozoo.org/#16_byte_intros https://nanogems.demozoo.org/#16_byte_intros As well as 32,64 and so on ... It even goes down to 8(!) Byte productions
  - tromp 6mo ago
    You can do amazing things in 8 bytes [1]. [1] https://tromp.github.io/blog/2026/01/28/largest-number-revised https://tromp.github.io/blog/2026/01/28/largest-number-revis...
    - HellMood 6mo ago
      You can (on real MSDOS!) go as low as 6 bytes https://www.pouet.net/prod.php?which=63538 https://www.pouet.net/prod.php?which=63538 But most people wouldn't find that visually satisfying The technical details why this works are very interesting though :)
      - senfiaj 6mo ago
        I guess anything that is less than 7 bytes can be brute forced.
        HellMood 6mo ago
parkertomatoes 6mo ago
Audio doesn't work, but here's an emulator link https://parkertomatoes.github.io/v86/?type=com&content=aACgB7ATzRCDxyh1GLCb5kD0RYnoLR4LcgWANtkBBORg%2Fsh0K7jNzPfniegtHgyJ0XIedBMoxZOI8CxN9ugo44jQBID26DjjsCp0aH1HeAHDieg9Hgp8PaggdQL20CQ%2FBJQAwXgvgO0seCq7uAGJ6C0eC3IFNFUPuwcPrMgSqBB0AvbQJR4ekQDriwfT6LPXJAPXdR%2BwloT2eRmA7nN4FIno9vaSBID26gHqkjDG9u7UCQTUqulQ%2F3AP9H3893xfsH7w%2FwD%2FwH%2Fwt%2FC7fLu8u5%2B7f3f%2F%2F%2Fz%2FFSwT https://parkertomatoes.github.io/v86/?type=com&content=aACgB...
- HellMood 6mo ago
  The sound works in DosBox-X if you use the providesd config file It also works on real old DOS PCs (or Windows XP/98 "DOS") but it would require changing a few bytes, mainly to setup UART MIDI mode
s3anw3 6mo ago
This takes me back to the NES era, where developers squeezed entire worlds into a few kilobytes of ROM. What blows my mind here is that even the NES had ~40KB of program space — and this entire boss fight, complete with sprite animation, scrolling landscape, and MIDI music, fits in 256 bytes. The NES ROM header alone is 16 bytes. Incredible work.
vermilingua 6mo ago
Another incredible 256b demo: https://linusakesson.net/scene/a-mind-is-born/ https://linusakesson.net/scene/a-mind-is-born/
- HellMood 6mo ago
  Absolutely! For all lovers of 256Bb intros (and 128,64 and so on) there is a curated "best of" selection maintained by Demosceners : https://nanogems.demozoo.org/#256_byte_intros https://nanogems.demozoo.org/#256_byte_intros "A mind is born" is of course included there =)
- senfiaj 6mo ago
  This one as well https://frankforce.com/city-in-a-bottle-a-256-byte-raycasting-system/ https://frankforce.com/city-in-a-bottle-a-256-byte-raycastin...
HellMood 6mo ago
https://www.pouet.net/prod.php?which=105909 https://www.pouet.net/prod.php?which=105909 The "silent" version is only 219 bytes A new version that adds new features into the remaining bytes is in the works
rob74 6mo ago
Hate to be that guy, but I just can't help it: this is an impressive demo, but for me a "boss fight" is something interactive, which this program obviously isn't. That's probably the reason why the title of the article is (now?) simply "Endbot", while the name of the HTML file is (still?) "A_whole_boss_fight_in_256_bytes.html".
- HellMood 6mo ago
  it's fine, you're right ;) i'm thinking of making that interactive, remove (a bit of) sound and plot timing (which takes surprisingly many bytes!) but i won't spoil anything until it's ready ;)
JoshBlythe 6mo ago
What a throwback! Reminds me of older gameboy games! Really nice project!
gavinray 6mo ago
My favorite SNES game (Uncharted Waters 2) is a 2MB ROM. I think about that every time I send a screenshot. The depth, complexity, and audiovisual beauty of that game stuffed into a space roughly a few times larger than a capture of my 1440p monitor in 2026.

130 points by HellMood 6mo ago

Technical write up for "Endbot" 256 bytes MSDOS program with plot, sync, sound, and payoff. Released April 4th at Revision Demoparty 2026.

ale42 6mo ago

Didn't run it (yet) but it looks nice. Great that some people are still able to optimize code! I'm wondering if this would run on actual hardware (VGA + a sound card supporting MPU401 emulation)

bitwize 6mo ago
We're gonna find that Claude Mythos can do something like this in 255 bytes
- HellMood 6mo ago
  I mean now that the (human written) source for this is out in the wild, of course it can ;)
- streetfighter64 6mo ago
  Optimizing away one byte of this, given the source code? Yeah, could happen. Making a good 256 byte demo from scratch? No way.
  - HellMood 6mo ago
    I mean, give it a try? the source is right there ;)
HellMood 6mo ago
I ran a patched version of it on WinXP (DOS NTVDM), the sound works there! But it requires a few extra bytes to enable MIDI UART Mode first. On DosBox-X, this can simply be set in the config ;)

lucb1e 6mo ago

That domain is such a blast from the past for me. I spent so many hours working on projects with free webhosting as a teen! dang/HN: this domain should probably be added to the list where the subdomain is shown next to the title, since subdomains are users' webspaces. (Might be a good candidate for the public suffix list: "[DNS labels] under which Internet users can (or historically could) directly register names".)

flopsamjetsam 6mo ago

I clicked on this fearing it was a "256 bytes of JS" (plus X GB of browser), and was pleasantly surprised it was actually 256 bytes.

rustystump 6mo ago
Why is that bad? If the bytes could easily run within the same constraint in another env/language why the hate? I am with u on the excessive ram of browsers. It is insane. Still, it is one of the most portal and easy ways to share something. Heck, u can run a dos emulator in your browser.
- senfiaj 6mo ago
  Probably because JS has larger runtime, in JS you don't have to write about most of the low level code. So it's easier to squeeze code in JS than in ASM or machine code.
- layer8 6mo ago
  This is probably in reference to things like Dwitter.net (https://news.ycombinator.com/item?id=46557489 https://news.ycombinator.com/item?id=46557489), where the browser (plus the Dwittet-specific runtime harness) contributes significantly higher-level functions than traditional demoscene targets like DOS PCs. It’s just a different thing. I see no “hate”, only an expression of preference for “bare-metal” demos.
  - selcuka 6mo ago
    Here's a 13-byte demo that runs on Chrome browsers: chrome://dino
- irishcoffee 6mo ago
  It is misleading to say "I wrote X in 1k bytes" when those 1k bytes were library calls to library calls totaling 300MB.
  - 6mo ago

Anmol-Baranwal 6mo ago

[dead]

philxor 6mo ago

And it came in 5th place in the competition. The winner was this one which is 16 bytes... https://www.youtube.com/watch?v=QKLhH_ANwIc https://www.youtube.com/watch?v=QKLhH_ANwIc

omoikane 6mo ago
Writeup: https://www.reddit.com/r/tinycode/comments/1se0iyt/writeup_for_16_byte_intro_rainbow_surf_1st_place/ https://www.reddit.com/r/tinycode/comments/1se0iyt/writeup_f...
HellMood 6mo ago
The demoscene has a curated collection of "best 16 bytes ever" https://nanogems.demozoo.org/#16_byte_intros https://nanogems.demozoo.org/#16_byte_intros As well as 32,64 and so on ... It even goes down to 8(!) Byte productions
- tromp 6mo ago
  You can do amazing things in 8 bytes [1]. [1] https://tromp.github.io/blog/2026/01/28/largest-number-revised https://tromp.github.io/blog/2026/01/28/largest-number-revis...
  - HellMood 6mo ago
    You can (on real MSDOS!) go as low as 6 bytes https://www.pouet.net/prod.php?which=63538 https://www.pouet.net/prod.php?which=63538 But most people wouldn't find that visually satisfying The technical details why this works are very interesting though :)
    - senfiaj 6mo ago
      I guess anything that is less than 7 bytes can be brute forced.
      - HellMood 6mo ago

parkertomatoes 6mo ago

Audio doesn't work, but here's an emulator link https://parkertomatoes.github.io/v86/?type=com&content=aACgB7ATzRCDxyh1GLCb5kD0RYnoLR4LcgWANtkBBORg%2Fsh0K7jNzPfniegtHgyJ0XIedBMoxZOI8CxN9ugo44jQBID26DjjsCp0aH1HeAHDieg9Hgp8PaggdQL20CQ%2FBJQAwXgvgO0seCq7uAGJ6C0eC3IFNFUPuwcPrMgSqBB0AvbQJR4ekQDriwfT6LPXJAPXdR%2BwloT2eRmA7nN4FIno9vaSBID26gHqkjDG9u7UCQTUqulQ%2F3AP9H3893xfsH7w%2FwD%2FwH%2Fwt%2FC7fLu8u5%2B7f3f%2F%2F%2Fz%2FFSwT https://parkertomatoes.github.io/v86/?type=com&content=aACgB...

HellMood 6mo ago
The sound works in DosBox-X if you use the providesd config file It also works on real old DOS PCs (or Windows XP/98 "DOS") but it would require changing a few bytes, mainly to setup UART MIDI mode

s3anw3 6mo ago

This takes me back to the NES era, where developers squeezed entire worlds into a few kilobytes of ROM. What blows my mind here is that even the NES had ~40KB of program space — and this entire boss fight, complete with sprite animation, scrolling landscape, and MIDI music, fits in 256 bytes. The NES ROM header alone is 16 bytes. Incredible work.

vermilingua 6mo ago

Another incredible 256b demo: https://linusakesson.net/scene/a-mind-is-born/ https://linusakesson.net/scene/a-mind-is-born/

HellMood 6mo ago
Absolutely! For all lovers of 256Bb intros (and 128,64 and so on) there is a curated "best of" selection maintained by Demosceners : https://nanogems.demozoo.org/#256_byte_intros https://nanogems.demozoo.org/#256_byte_intros "A mind is born" is of course included there =)
senfiaj 6mo ago
This one as well https://frankforce.com/city-in-a-bottle-a-256-byte-raycasting-system/ https://frankforce.com/city-in-a-bottle-a-256-byte-raycastin...

HellMood 6mo ago

https://www.pouet.net/prod.php?which=105909 https://www.pouet.net/prod.php?which=105909 The "silent" version is only 219 bytes A new version that adds new features into the remaining bytes is in the works

rob74 6mo ago

Hate to be that guy, but I just can't help it: this is an impressive demo, but for me a "boss fight" is something interactive, which this program obviously isn't. That's probably the reason why the title of the article is (now?) simply "Endbot", while the name of the HTML file is (still?) "A_whole_boss_fight_in_256_bytes.html".

HellMood 6mo ago
it's fine, you're right ;) i'm thinking of making that interactive, remove (a bit of) sound and plot timing (which takes surprisingly many bytes!) but i won't spoil anything until it's ready ;)

JoshBlythe 6mo ago

What a throwback! Reminds me of older gameboy games! Really nice project!

gavinray 6mo ago

My favorite SNES game (Uncharted Waters 2) is a 2MB ROM. I think about that every time I send a screenshot. The depth, complexity, and audiovisual beauty of that game stuffed into a space roughly a few times larger than a capture of my 1440p monitor in 2026.