In case anyone was wondering, the IOCCC specifically permits LLM use in their guidelines.
"The IOCCC has a rich history of remarkable winning entries created by authors who skillfully employed various techniques (often their own tools) to develop their code."
In my experience LLMs were pretty good at deobfuscating many entries (including mine) but very awful at generating any significantly obfuscated code. So obfuscation can be regarded as a truly humane art---at least for now.
It's a bit annoying getting frontier models to even work on IOCCC code because of "safety", but even if you get around that LLMs just aren't very good at it. Obfuscating code involves a level of creativity and deviousness that LLMs struggle to meet.
The GameBoy emulator's code also looks like the GameBoy. Slow clap this is insane, definitely my favorite entry.
https://github.com/ioccc-src/winner/blob/master/2025/ncw1/pr...
The author, Nick Craig-Wood, is the creator of rclone!
Damn, that is cool! Looking at me typing css & php...
My favorite is the 366-byte C program emulator that can run Linux and Doom [0]. The VM implements an OISC - a One Instruction Set Computer [1].
[0] https://github.com/ioccc-src/winner/blob/master/2025/cable/p...
[1] https://github.com/ioccc-src/winner/blob/master/2025/cable/R...
The website itself is obfuscated, it’s not easy to find the C sources at all!
Can jump straight to https://www.ioccc.org/2025/#inventory
In case anyone was wondering, the IOCCC specifically permits LLM use in their guidelines.
"The IOCCC has a rich history of remarkable winning entries created by authors who skillfully employed various techniques (often their own tools) to develop their code."
Tis a pity to not have LLMs compete, given level of obfuscation they be capable of.
In my experience LLMs were pretty good at deobfuscating many entries (including mine) but very awful at generating any significantly obfuscated code. So obfuscation can be regarded as a truly humane art---at least for now.
It's a bit annoying getting frontier models to even work on IOCCC code because of "safety", but even if you get around that LLMs just aren't very good at it. Obfuscating code involves a level of creativity and deviousness that LLMs struggle to meet.
So like at a film festival, 90% of the entries won a price, but unlike a film festival there's not a single best. Weird, like modern education.