CAMEL – Crossfigure with Advanced Math, Elevated Logic

Crosswords test your vocabulary. CAMEL tests your number sense.

Every cell holds a digit, not a letter. Every clue is a real mathematical
property — primes, perfect squares, palindromes, GCDs, digit sums — and
every grid crosses dozens of these properties into one tightly-constrained
puzzle. There's exactly one number that fits. Your job is to find the chain of
logic that gets you there.

If you've outgrown crossnumber apps that recycle the same three clue types,
this is the next step up.

WHAT MAKES IT DIFFERENT

• Real number theory, not arithmetic trivia. Clues draw from primes,
divisibility, greatest common divisors, perfect squares, palindromes,
digit sums and products, ascending and descending digits — and the odd
rarity like an emirp or a Harshad number — the same ideas that make number
theory fun in the first place, dressed as puzzle clues.
• Every puzzle is logic-solvable. No guessing required: every published grid
can be fully deduced from its clues alone.
• Clues actually cross-reference each other. "This entry equals double that
one." "These two share a digit." Relational clues turn the grid into a real
constraint-satisfaction puzzle, not a list of independent riddles.
• Hints that teach, not just reveal. Stuck? Solve Step shows you the next
logical deduction — including the rare case where one digit becomes
certain before the whole entry does — and tells you whether it follows
straight from a clue's own logic or needed the rest of the grid first.

FOUR PACKS, YOUR PACE

• Mini Grids (Easy) — 16 puzzles on compact 2×3 grids. The on-ramp for
"wait, that's a clue?" moments.
• Square Grids (Medium) — 20 puzzles on 3×3 grids where every entry crosses
two others.
• Compact Grids (Medium) — 31 puzzles on 3×4 grids with longer entries and
richer constraint graphs.
• Hard Grids (Hard) — 20 puzzles with dense, relational clue networks.
Multi-step deduction chains start here.
• A free Daily Challenge, every day.

BUILT FOR ACTUAL SOLVING

• Pencil-mark candidate digits per cell, exactly like a paper puzzle.
• Per-entry notes for tracking your own reasoning.
• Undo/redo, and a Check button that verifies your filled cells without
spoiling the rest.
• Dark mode for late-night solving sessions.
• Achievements, streaks, and daily/weekly/all-time leaderboards if you like
to track progress — entirely optional if you don't.

All 87 puzzles are free, plus the Daily Challenge — no ads, no subscription,
and no account required to play. Nothing in the game is locked or purchasable
today; Google Play's "In-app purchases" label covers optional hint packs that
are planned for a later update.

Crossfigure. Crossnumber. Whatever you call the genre — this is the advanced-
math, elevated-logic version of it.