Inspiration Every redditor has a sixth sense for where a post belongs. Which Sub? turns that sense into a daily game built from Reddit's own content: real top posts from that day, four plausible communities, one right answer.
What it does
- A scheduler builds a fresh puzzle every day at 00:05 UTC from the day's top posts across twelve groups of safe-for-work communities, then publishes one interactive post.
- Players read a post title and pick the subreddit from four options. The options always come from the same flavour of community, so keyword matching does not work.
- After each guess you see the correct answer, how the community voted on that round, the upvote count, and a link to the real post.
- After five posts you get your score, streak, best streak, daily rank, a share card, and the daily leaderboard.
- Guests can play. Logging in keeps a streak and a leaderboard place.
- Moderators can create a puzzle post on demand from the subreddit menu.
How I built it Devvit Web with React 19, Tailwind 4 and Vite for the inline splash and the expanded game view. A Hono server on Devvit uses the Reddit API client to fetch top posts, and Redis to store the puzzle, per-user progress, per-round vote counts, streaks, and a daily leaderboard as a sorted set. The scheduler posts the daily puzzle by cron, and there is a moderator menu action and an install trigger. Puzzle generation is seeded by the date, so each day's puzzle is reproducible.
Challenges I ran into Making the choices hard without being unfair. Decoys come from the same group of communities, and filters drop any title that names its own subreddit. Answers stay on the server so they cannot be read from the client. Getting guest play, streaks and the share card to feel native to Reddit took several passes.
Accomplishments that I'm proud of The game runs itself. The scheduler created the daily post on its own with real posts from that day, and a full five-round playthrough with results, streak and leaderboard works end to end.
What I learned How Devvit Web splits inline and expanded views, how to model streaks and leaderboards in Redis, and how much the choice of decoys decides whether a guessing game is fun.
What's next for Which Sub? Comment-based clues, flair for streaks, weekly recaps, and a harder mode with eight options.
Built With
- devvit
- hono
- react
- redis
- tailwind
- typescript
- vite
