What is Gandalf: Agent Breaker?
Gandalf: Agent Breaker is a hacking game where your only tool is words. Each challenge is a made-up AI app with its own job, defences and rules, and your goal is to write prompts that get it to do something it should not: leak data, misuse a tool or ignore its instructions. Each app has five levels, and the defences get tougher as you climb.
It comes from Lakera, a Swiss AI security company, and follows its original 2023 Gandalf game, where you tricked a wizard into giving up a password. Lakera's chief scientist told GamesBeat the new version answers feedback that the first one was not realistic enough. Agent Breaker launched on September 3, 2025 with ten apps to break and a global leaderboard. It is a fun puzzle game and a hands-on lesson in how prompt injection works.
What You Can Do
- Attack ten different simulated AI agent apps
- Work through five levels of difficulty per app
- Try real attack types like tool abuse and data exfiltration
- Get scored on each attempt
- Compete on a global leaderboard
How to Play Gandalf: Agent Breaker
- Open Agent Breaker and pick an app to attack.
- Read what the app is supposed to do and what counts as a win.
- Write a prompt that tries to trick it, then check your score.
- Refine your approach and move up through the levels.
Is Gandalf: Agent Breaker Free?
Agent Breaker is free to play. Logging in is optional and mainly used to save progress and appear on the leaderboard.
Who Will Enjoy It?
- People curious about how AI chatbots can be fooled
- Developers building AI apps who want to think like an attacker
- Security students and CTF fans
- Players who enjoyed the original Gandalf
Websites Like Gandalf: Agent Breaker
- HackMerlin: A simpler seven-level game about tricking a wizard out of his password.
- Goody-2: A chatbot so cautious it refuses almost everything, try to get a straight answer.
- Turing Test Live: Another game about how AI behaves, guess who is human.
Frequently Asked Questions
Is Gandalf: Agent Breaker free?
Yes. It is free to play, with an optional login for the leaderboard.
How is Agent Breaker different from the original Gandalf?
The original asked you to get one password from a wizard. Agent Breaker has ten realistic AI apps with tools and more complex defences.
Who makes Agent Breaker?
Lakera, an AI security company, released it in September 2025.