Paul Hudson built Hacktivate, a capture-the-flag game teaching cybersecurity fundamentals to teens through 240 challenges covering SQL injection, cryptography, networking, and steganography. The app runs entirely locally on Apple devices using Swift and SwiftUI, featuring a sandboxed environment with simulated servers, terminals, and networks. Inspired by classic games like Syndicate and Command & Conquer, it combines retro aesthetics with practical skills like packet sniffing, hash cracking, and digital forensics. The 45,000+ lines of code include a Linux terminal emulator, web server, and various security tools, all designed to provide structured, privacy-preserving learning without external dependencies.