May game – Sudoku and spec-driven development

I'm late with the May game, but here it is: iTrond Sudoku — built using a spec-driven approach.

As part of my Game Dev 2025 series, see I will build one game per month in 2025.

You can try the finished version here: Play the finished Sudoku

I wanted to build a digital Sudoku and decided to try a more structured approach this time: spec-driven development using speckit. I wrote a specification that described how the game should behave and used that spec to guide development. This made the process much cleaner and helped keep track of requirements, edge cases and test coverage.

I used AI to help generate and refine the specs, and kept the spec files in a dedicated directory.

The approach allowed me to capture clarifications from development directly into the spec, which helped reduce misunderstandings and sped up iteration.

I tested this and came up with this solution (take 2) with only a few interventions from my side:

The finished solution can be tried here: Play the finished Sudoku

Implementation details

The game is built with React and TypeScript and follows a modern web app structure with components for the board, statistics and game logic. Everything was developed against the spec (spec.md), and tasks were generated and tracked with speckit. That made it easier to keep functional and non-functional requirements in sync and well-tested.

Recommended pro app

My friend Terje Molle has built a professional Sudoku app for iOS: SudokuWorldTournament. If you want serious competition, check it out.