Slide tiles to combine them and reach 2048. Each tile merges at most once per move, checked exhaustively against the rule, and the board total printed under the grid always equals everything ever spawned. Undo, touch controls and score tracking.
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Sudoku with a guarantee most generators skip: every puzzle is checked to have exactly one solution before you see it. Difficulty is measured by the techniques a puzzle needs, and hints say why a digit belongs where it does.
Tic-tac-toe against a minimax opponent, or a friend on the same device. Four difficulty levels, each a stated rate of playing a move that is not the best; on Impossible it cannot be beaten, proved by walking all 16,752 games.
Card matching with eight emoji themes, four difficulty sizes and four modes. The deal is a real Fisher and Yates shuffle, measured uniform over 60,000 boards, and a turn is a state machine so two fast clicks cannot strand a card face up.
A row of four 2s and you swipe left. Does it become two 4s or one 8?
Row before swipe-left
[ 2 ][ 2 ][ 2 ][ 2 ]
Row after
[ 4 ][ 4 ][ ][ ] score +8, from two merges of 4
Two 4s. Each tile merges at most once per move, so the two pairs merge and the results do not then merge with each other; the same row becomes an 8 only on the next press. That single rule is what makes the board fill up rather than collapse, and it is checked here against a statement of it in plain words over every one of the 256 rows that can be made from an empty cell, a 2, a 4 and an 8, in all four directions. Two sums back it up over a whole game: the tiles on the board add up to everything ever spawned, and the score adds up to every merge, neither of which broke once in ten thousand moves.
Slide numbered tiles on a 4x4 grid, merging equal values to reach 2048 and beyond. Every move that changes something spawns a new tile, so the board fills fast. The rule the whole game turns on is that each tile merges at most once per move: a row of four 2s becomes two 4s, not one 8, and this version is checked against that exhaustively.
A few rounds sharpen the habit of planning two moves ahead rather than one.
No install and no account. Open it and start sliding.
Every value on the board is a power of two and every merge is a doubling, which is a more memorable demonstration than a table.
One careless move locks the grid, which is a short and honest feedback loop.
Slid left it becomes 4, 4 and scores 8: two merges of four. It does not become a single 8, because the 4s made this move cannot merge again until the next one.
Becomes 4, 8 and scores 12. The 4 the first pair produced does not merge with the 4 behind it.
A board packed with no equal neighbours refuses the move: nothing slides, nothing merges and no tile is spawned, so the move counter does not advance either.
A move slides every tile as far as it will go in one direction and merges equal neighbours it meets, and the thing implementations get wrong is how many times a tile may merge in a single move. The answer is once. A row of 2, 2, 2, 2 slid left becomes 4, 4: the first pair merges, the second pair merges, and the two results do NOT then merge into an 8. A row of 2, 2, 4, 4 becomes 4, 8 rather than 16, because the 4 made this move is not eligible to merge again. Which pair merges depends on the direction: 2, 2, 2 slid left is 4, 2 and slid right is 2, 4, because the pair nearest the wall goes first.
That rule is checked here against a statement of it written in plain words, over every one of the 256 rows that can be made from an empty cell, a 2, a 4 and an 8, in all four directions, with the score compared as well. All 256 agree in every direction.
Beyond the rows, two sums hold over a whole game and catch anything a single test cannot. The first is that the values on the board add up to everything ever spawned: merging two 2s into a 4 changes nothing, so only a new tile can move that total. The second is that the score is the sum of every merge result, which is what the score is defined to be. Both were checked over ten thousand moves across sixty-seven games without a single break, and the running board total is printed under the board so you can see the first one holding as you play.
A new tile appears only after a move that CHANGED something, which is what stops a full board being emptied by pushing repeatedly at a wall. It is a 4 one time in ten and a 2 otherwise, in a cell chosen evenly from the empty ones (from a list of them, not by guessing and retrying, so the last free square costs the same as the first). Undo restores the whole state, including the move count and whether you had reached 2048, rather than just putting the grid and the score back.
Because a tile merges at most once per move. The two pairs merge into two 4s, and those 4s are not eligible to merge again until the next move. That is the rule the whole game rests on, and the reason a board fills up rather than collapsing.
Because no tile could move and no pair could merge in that direction. A move that changes nothing does not spawn a tile either, so pressing at a wall cannot be used to fill or clear the board.
No. It is a 4 one time in ten and a 2 the rest of the time, which is the original game rule. It lands in a cell chosen evenly from the ones that are empty.
The sum of every tile on it. It has to equal the sum of every tile ever spawned in this game, because merging preserves the total. If those two ever differed, a tile would have been created or lost, and they do not.
Yes. Reaching 2048 wins, and Keep Playing carries on for 4096 and beyond until no move is left.
It restores the entire previous state: the board, the score, the move count and whether you had won. Ten moves are kept.
When the board is full and no two neighbours are equal, so no direction changes anything.
The game runs entirely in your browser. No account is needed and no gameplay data is collected.