DropLine

A calm, offline number-sliding puzzle that fits in one hand.

How to play
Swipe the board in any direction and every tile slides to the far edge at the same time. When two tiles with the same number meet, they merge into one tile worth twice the value, and every merge adds to your score. A tile created by a merge never merges again in the same move, so each swipe is a small puzzle of its own. After every valid move a fresh tile (2 or 4) appears in a random empty cell; an invalid swipe changes nothing and adds no tile. The run ends when the board is full and no merge is possible in any direction.

Classic mode
Play endlessly on a standard 4x4 board and aim for the highest tile and score you can reach. Your highest score, highest tile and number of games are tracked automatically.

Fifty challenge levels
Challenge mode offers 50 fixed starting positions grouped into three goal types:
- Reach a target value within a step limit.
- Clear fixed blocks that take one or more pushes to remove.
- Build a target tile while keeping a chosen corner empty.
Every challenge starts from a fixed, reproducible layout, so success depends on your moves, not on luck. Each completed level is recorded together with your lowest step count.

One-step undo
You may undo the most recent move once per run. Undo restores the board, the score and the random state together, so it can never be used to fish for different tiles. Runs that use undo are tracked separately from clean runs.

Learn as you play
A built-in guide explains the movement rules, single-time merging, tile generation and ending conditions using a small 3x3 example board.

Preferences
Tune the experience to your taste: swipe sensitivity, merge animation, sound feedback, light or dark theme, number font size, and an assist texture for empty cells.

Your data stays on your device
The game is fully offline. Scores, records and challenge progress are stored only in local storage on your device. No account, no ads, no in-app purchases and no network connection are required. A privacy notice inside the app describes how your data is handled.