A Sudoku variant played with HTML tags and JavaScript keywords instead of numbers — our take on an interview-brain warmup, built as a product, not a side project.
Sudoku is a good warm-up for pattern recognition. It has nothing to do with code. We wanted both at once.
The idea
Code-Doku keeps Sudoku's core rule — each symbol appears exactly once per row, column, and box — but swaps digits for HTML tags or JavaScript keywords. Solving it means recognising syntax at a glance, the same reflex you use scanning a diff or a code review.
Why we built it as a real product, not a demo
100 progressive stages, a grid that grows from 3×3 to 8×8, and a global leaderboard — the same attention to scope, difficulty curve, and polish we'd put into a client's MVP. It's a small product, but it's not a throwaway one.
Who it's for
Developers warming up before a technical interview, engineers who like puzzles on a break, and anyone curious what a coding studio builds when the "client" is our own developer audience.