About Brain Challenge

Brain Challenge is a small independent puzzle site: 1000 levels, five puzzle types, no sign-up, no download, no paywall.

Why build another puzzle site?

Most “brain training” apps are subscription products built around a daily streak mechanic. I wanted the opposite: something you can open for five minutes, solve two puzzles, and close without being asked for a credit card or an account.

How the levels work

Every level is generated from its own number, which means level 617 is always the same puzzle — you can share a link to it, come back tomorrow, and it will not have changed. The five types are:

• Odd one out — a grid where one character or shape is mirrored or rotated
• Hidden digit — a digit hiding among look-alike letters
• Number patterns — sequences with rules from simple addition to squares and ×2+1 chains
• Picture idioms — emoji and number clues for four-character Chinese idioms
• Logic riddles — ordering and comparison deductions

Difficulty

Levels 1–100 are an introduction: small grids, generous timers. Levels past 600 use 6×6 grids, 15-character strings and multi-step number rules. Nothing is locked behind a payment.

Is it really free?

Yes. The site is a static HTML/JavaScript bundle, which keeps hosting costs near zero. Advertising, when present, is what pays for the domain.

Feedback

If a puzzle is broken or ambiguous, tell me which level number and what went wrong: qqqqq413954195@gmail.com. Ambiguous puzzles are the most useful reports — they usually mean a rule is not obvious enough.