The International Obfuscated C Code Contest announced its 2025 winners on July 5, naming 23 programs that achieved creative uses of the C language.

Founded in 1984, the IOCCC asks participants to write C programs that are intentionally hard to read while remaining correct; judges introduce a new category for each winning entry. The 2025 competition included categories such as Best imaginary emulator, Best real emulator, and Most likely to dazzle.

Adrian Cable’s 366‑byte Subleq emulator, built with LLVM and capable of running Linux, was recognized for its application in software preservation. The program uses a single instruction, Subleq, and can be compiled to execute any architecture through an emulator.

Nick Craig‑Wood received three awards: a 66‑line Game Boy emulator formatted to resemble the console, a fractional Commodore 64 emulator written in FRACTRAN, and a Unicode‑based Forth program that generates a spinning Mandelbrot zoom.

Yusuke Endoh earned his 23rd win with a Nixie tube simulator whose source code highlights digits in color to mimic tube output, a Lichtenberg figure generator, and a self‑modifying program that outputs the diff of its own patches.

Tomoya Ishida’s 36‑line entry produced a five‑minute ambient sound file containing synthetic seashore sounds, earning the Most soothing award.

Jonah Uellenberg’s Pong program is a quine that displays its own source as the game screen; each compilation updates the source and the game frame, allowing play through repeated compilation.

Other notable entries include a 54‑line roguelike labeled Most likely to teleport, an ASCII‑animated Doctor Who title sequence by jingp49, and a single‑variable program that computes many digits of Euler’s constant.

The IOCCC continues to demonstrate the creative limits of the C language, and future contests are expected to introduce new categories and inventive solutions.