Make ten on a 5×5 grid: a full row or column clears when it adds up to a multiple of 10. Every level is checked by a solver before it ships — no dead ends, ever.

Decka deals like a card game and solves like a logic puzzle. You hold up to five numbered cards, you choose where each one goes, and nothing on the board moves unless you move it.

HOW IT PLAYS
• Tap a card, tap a square. That is the whole control scheme.
• A line clears only when all five cells are full AND its numbers add to 10, 20, 30, 40 or 50.
• No gravity: cards you place stay exactly where you put them.
• 40 cards per level, four of each number from 1 to 10 — a counter strip shows what is still in the deck.
• Empty the board to win the level.

NEVER A DEAD END
Here is the part that makes Decka different. Every level is generated, then handed to a solver that plays it all the way to an empty board before the level is allowed to ship. The exact deck order you are dealt is certified playable down to the last card. So when a board looks impossible, it isn't. The move exists. Finding it is the game.

SIX CHAPTERS, AND IT KEEPS DEALING
Warm-Up, Tens Town, Cascade City, Overflow, Summit, Endless. The boards fill up, the spare space tightens, chain clears start paying real points, and from level 51 a harder line appears: five cards that total 40. Past Endless the campaign keeps generating fresh certified boards, forever.

PUZZLE LEVELS, EVERY FIFTH LEVEL
At 5, 10, 15 and on, the rule flips: nothing clears. Fill the whole 5x5 grid so that every row AND every column lands on a multiple of ten. You are dealt exactly the cards you need — placing them in the right squares is the entire problem. Same arithmetic, opposite instinct.

DAILY CHALLENGE
One daily puzzle to fill in, built from the date, the same board for everyone. Your whole hand is dealt at once: no deck, no draw, no shuffle — just the cards and the grid. Solve it and your streak grows. Come back tomorrow for the next board and the daily bonus.

YOUR TOOLKIT
UNDO — take back a move, up to three moves deep. Free from level one, and refreshed on every new level.
SHUFFLE — hand your cards back and take a fresh deal. Unlocks at level 6.
WILD CARD — name any number from 1 to 9 and add that card to your hand. Unlocks at level 6.
Shuffle and Wild Card each arrive with two free uses: a one-time grant when they unlock, not a per-level refill. After that they cost the rewards you earn by clearing boards. None of it is required — every level is solvable with no tools at all.

NO TIMER, NO PRESSURE
No countdown. No lives. No bad luck to blame. Think for two seconds or two minutes — the board waits. It is quiet mental arithmetic: a brain training puzzle you can actually play at 11pm without your pulse going up.

PLAYS ANYWHERE
Decka is an offline puzzle game: no connection needed to play, on the bus, on a plane, in a basement. No account, no sign-up, nothing to register. Your progress is kept on your device. Free to play, and no purchase is required to finish any level. Six languages: English, French, Spanish, German, Italian and Portuguese, auto-detected and switchable anytime.

MADE FOR PEOPLE WHO LIKE
Solitaire, sudoku, number puzzles, card puzzles, logic puzzles, or plain mental math. Decka sits in that corner of the shelf — the calm one, ivory cards on green, no stopwatch anywhere.

If you think you are stuck, remember: the solution exists, and it was proven before you ever saw the board.

Your move.