Number Merge Game
Slide every tile up, down, left or right and merge equal pairs. A tile merged this turn cannot merge again until another turn. A new tile appears in an empty cell only after a move changes the board. Replaying the same seed and directions reproduces the board, score and spawns. Reach the target to win; a board with no blank and no equal adjacent pair ends the game.
Key features
- Choose a 4×4 or 5×5 board and a target from 128 to 8192
- Exact directional compression with one merge per source tile and merge-value scoring
- Seeded pair of starting tiles and a 2 or 4 spawn after each effective move
- Win and blocked-board detection with undo that rewinds the random generator
- Arrow keys, touch swipe and on-screen buttons plus move history
- Local JSON save/load that replays board, score and spawn log for validation
How to use
- Choose a 4×4 or 5×5 board, target tile and integer seed from 0 to 4294967295, then start a new game.
- Focus the grid and press an arrow key, swipe it, or use an on-screen direction button. Each merged tile adds its new value to the score.
- Read the score, turn count, new tile position and move log. A move that changes nothing causes no spawn and is not recorded.
- Undo removes the last effective move and rewinds the generator. Repeating that direction recreates the same tile in the same place.
- Download the current game as JSON, or paste or select an earlier save. The board, score and spawn log are recomputed from the saved moves.
Use cases
- Challenge a friend with the same seeded number-tile puzzle
- Review merge order and score gains in the move log
- Save an in-progress game locally and continue later in your browser
Frequently asked questions
Can a tile merge twice in one move?
No. Tiles are compressed toward the chosen edge and equal pairs merge once. For example, 2·2·2·2 becomes 4·4, not 8, in one turn.
When does a new tile appear?
One 2 or 4 appears in an empty cell after a move actually changes the board. A direction that changes nothing leaves the score, seed state and turn count unchanged.
Will the same move after undo give the same result?
Yes. Undo removes the last direction and replays from the seed, so the same direction reproduces the same spawn position, value and score. You can undo repeatedly back to the start.
How are win and game over decided?
A tile at or above the selected target wins. Below target, a full board with no equal horizontal or vertical neighbors is game over. Both phases stop further moves; undo or start a new game to play again.
Can I load any arbitrary board in JSON?
No. The board, score and spawned tiles are replayed from the seed and legal move list and compared with the saved values. A modified or malformed save leaves the current game untouched.
Is the game saved to a server?
No. Play stays in this browser tab, and JSON download/import happens only when you request it. There is no automatic account sync.
Privacy
Your game state and seed are processed in this browser tab. The tool does not submit the game to a server or save it automatically.
Comments & questions