Arx
Competitive hacking for security students, and a record of every flag they capture.
Started in September 2026. So far only the team building it has played it.
Arx is a place for people learning security to compete. You get something to break: an encrypted message, a disk image, a program with a password check, a picture with something hidden in it. Somewhere inside is a flag. Find it, submit it, and it counts. You can play alone or on a team, and matches put you against other players on the same challenges at the same time. Every flag you capture is checked when you submit it and stays on your profile, so over a year the profile turns into evidence of what you can actually do. Arx is in internal testing and is not open to the public yet.
Why it exists
People learning security practise on capture-the-flag challenges. You are handed something broken on purpose, a weak cipher or a program that checks its password badly, and hidden inside it is a short string called a flag. Find the flag and you have solved it.
Most of that work leaves nothing behind. A weekend competition ends and its scoreboard goes offline. A good solve gets posted as a screenshot in a group chat and scrolls away. Someone hiring a junior analyst has no reliable way to tell which student did the work, so Arx keeps it. A flag is checked the moment it is submitted, and it stays on the player's profile.
It started in September 2026, the same week one of us began a cybersecurity degree.
How it works
A challenge is something to take apart. An encrypted message, a disk image, a packet capture, a compiled program, an image or a sound file with something hidden in it. You work on it on your own machine with your own tools, and you submit the flag when you find it.
You can play alone or join a team. A match puts players on the same set of challenges at the same time, and the order they finish in is the result.
Red vs Blue is the other format. One team attacks a set of machines and the other team defends them, and both sides are scored for as long as the match runs.
Where it stands
Arx is in internal testing. The only people playing it are the people building it, and that stays true until the challenges hold up and the scoring can be trusted.
There is nothing to sign up for yet. The picture on this page is not the product. The interface is still changing, and we would rather not publish screens we are about to replace. When Arx opens, this page will say where to find it.
What it does
- Capture-the-flag challenges in cryptography, forensics, reverse engineering, steganography and OSINT
- Play alone, or on a team that shares one score
- Matches against other players on the same challenges, at the same time
- Red vs Blue: one team attacks a set of machines while the other defends them
- A profile that keeps every flag a player has captured
Run a security club, or teach a course?
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