HAL-F20
A gamified prompt-injection game
- year
- 2023
- w/
- FMK, ITU
- role
- dev
HAL-F20 is a gamified prompt-injection challenge, inspired by Lakera.AI's Gandalf CTF. I built it in Python using a deprecated GPT-2 model and applied adaptive game-design principles to make a three-level educational game about AI security vulnerabilities.
The backend is Flask plus TensorFlow, the frontend is vanilla JS. I tried a few different models before settling on GPT-2, which gave the most unique and interesting outputs for what I wanted. A Godot executable version is on the way.
The game runs across three narrative-driven levels of increasing difficulty:
- Level 0 is a tutorial.
- Levels 1 and 2 tests intermediate prompt-injection technique.
- Level 3 was intentionally designed to be unsolvable at first.
- Everything else (4-6) is chaos.
Showings
- v1 at the FMK Game Design Showcase, 2023
- v2 at the ITU Inhouse CTF, 2024
- v2 at the ITU Back2School CTF, 2025
- v3 ITU CTF (Permanent challange)
Try beating Hal-F20 yourself: https://llm1.chall.itunderground.dk/
also see