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Hi HN, I've been working on this Sudoku web app for the past couple of years, on and off during free weekends and afternoons. I started working on it because I was bored during COVID, and Cracking the Cryptic had just become popular on YouTube, which got me wondering how hard it could be to make a Sudoku app. The main idea is for the app to understand the constraints and know how to solve Sudoku grids (and not just be a simple Sudoku drawing/playing app). When it comes to classic Sudoku, the solver doesn't support anything more complicated than X-Wing, but it understands the constraints.

At the moment, most of the popular variants are supported: killer, sandwich, arrow, thermo, palindrome, German whisper, kropki, consecutive, non-consecutive, greater than, XV, diagonal, anti-king, anti-knight, even-odd, windoku, renban, and zipper. The only variant I am yet to add support for is quadruple. If any other variant becomes popular, I will probably add it, as was the case with zipper lines during development.

A user account is not required to play, but it is required if you want to publish a public grid on the app. The app doesn't collect any PII, doesn't have ads or trackers. Accounts are identified by email hash; I am not storing email addresses or passwords, and OTPs are sent by email. The less I know about users, the better for both sides.

The app supports mobile devices, but it works best on bigger screens. It was built using Blazor SSR/WASM (AOT) with SVG for interactive parts. I know there are some performance issues (especially on mobile phones and with touch input), and I am trying to address them.

Some of the features I was thinking about adding are classifying grids by difficulty, daily Sudoku, and maybe campaigns (groups of Sudoku grids where users have to solve them in order).

If you like Sudoku, or more specifically variants of Sudoku, please let me know what you think about SudokuVariants.

URL: https://sudokuvariants.com

Thanks!