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  fiLLr logo

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  a view of the game in hard difficulty

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  a medium puzzle in progress

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  100 weekly visitor stat for fiLLr

Inspiration

I wanted to create a puzzle that people could pick up and solve in just a few minutes, whether they're commuting, taking a break, or simply looking for a daily challenge. That idea became fiLLr: a bite-sized puzzle that's easy to learn, rewarding to master, and built on Reddit so every daily puzzle becomes a shared community experience.

What it does

fiLLr is a daily number-path puzzle built for Reddit. Players draw one continuous path that fills every cell while visiting each numbered node in order. It's easy to learn, but every puzzle requires careful planning and efficient routing to solve.

Features include:

• Two fresh puzzles every day, each available in Easy, Medium, and Hard.
• Global leaderboards ranked by fewest moves, then fastest time.
• Persistent Reddit user flair that tracks each player's progress over time.
• A community puzzle builder where anyone can create a puzzle, verify it's solvable, preview the solution, and publish it for others to play.

How we built it

Frontend

• Built with Phaser and TypeScript to deliver a fast, responsive puzzle experience.
• Real-time path validation ensures every move follows the puzzle rules as it's drawn.
• A shared input system provides a seamless experience across mobile and desktop.
• Local saves let players switch difficulties or return later without losing progress.

Backend

• Built with Hono, Devvit APIs, and Redis.
• Redis powers leaderboards, player statistics, Reddit flair, and community-created puzzles.
• Redis Sorted Sets keep rankings updated in real time, while scheduled jobs publish new daily puzzles automatically.
• Puzzle validation, rate limiting, and duplicate detection help keep community submissions fair.

Challenges we ran into

Getting the controls to feel great on both touchscreens and desktops was one of the biggest challenges. Mobile players expect forgiving gestures, while desktop players expect precision. We built a shared input pipeline that delivers a consistent experience across every device.

The community puzzle builder was another challenge. Every puzzle is automatically validated before it's published, ensuring players only encounter puzzles with valid solutions.

Accomplishments that we're proud of

• Built a complete community puzzle builder with automatic solvability validation.
• Created persistent Reddit flair that rewards long-term player progress.
• Delivered deterministic daily puzzles so every player competes on exactly the same challenge.
• Shipped a polished cross-platform experience that feels at home on both mobile and desktop.

What we learned

Building fiLLr taught us that making a puzzle game feel simple is anything but simple. We learned Phaser from scratch, built custom path-validation logic, and spent just as much time refining the input experience as we did designing the puzzles.

What's next for fiLLr

We're excited to expand player progression with unlockable themes, path colours, and cosmetic rewards, while introducing new challenge modes and more ways for the community to create and share puzzles. Our goal is to make fiLLr the go-to place on Reddit for daily logic puzzles.

Built With

• node.js
• phaser.js
• redis
• typescript