Wuzzit Trouble stands out as one of the few educational apps built on legitimate mathematical research rather than gamified flashcard drills. Designed in part by Stanford mathematician Keith Devlin, the game asks players to free little creatures called Wuzzits by turning gear-shaped locks. The core mechanic relies on integer partitions—finding different combinations of numbers that sum to a target—wrapped inside a mechanical puzzle.

Because the game focuses on problem-solving instead of speed, kids get space to think mathematically. There are no timers pushing frantic tapping, and no predatory microtransactions. It rewards strategy, trial, and error.

The massive catch is availability. The game has been delisted from both the Apple App Store and Google Play. Unless you already have it installed on an old iPad tucked away in a drawer, it exists mostly as a historical high-water mark for what good math game design looks like.