Reversing

Reverse-engineering a custom esolang stack machine to recover the flag.

Reversing a Python marshal bytecode maze generator seeded by an LCG to find the escape path.

Reversing a repeating-key XOR crackme that downloads the flag from catbox.moe.

Recovering the flag from TrueType GSUB ligature substitution rules.

Decompiling a compiled AutoHotkey executable to extract the flag.

Recovering a flag hidden via stack-string construction and XOR obfuscation.

Crackme that stores the bitwise NOT of the flag bytes; invert them to get the flag.

Extracting a flag hidden inside a PDF stream using FlateDecode and base64.

A single APK whose UI claims there’s nothing to see — the flag is split into three pieces hidden in a MainActivity field, a string resource, and a Compose theme getter.

An idle/clicker TCP game whose shop checks affordability against a stale cached balance but deducts from a fresh re-read; racing two sessions as the same user underflows an unsigned long to ~1.8e19 bits and buys the flag.