About

This tool is a dual-instance implementation of the sliding tile puzzle, designed for local competitive play. Unlike the standard single-player variant, this application runs two independent game logic threads simultaneously within the browser DOM, allowing two users to compete side-by-side on a single device.

The core mechanic relies on a deterministic sliding algorithm. When a directional input is triggered (Vector v), all tiles shift maximally in that direction. If two tiles of value x collide, they merge into a single tile of value 2x. The game ends when the grid is full and no adjacent tiles satisfy the condition tile_i,j = tile_neighbor.

Pro Tip: Use the "Tabletop Mode" toggle on tablets to invert Player 1's screen, enabling a face-to-face seating arrangement.

Formulas

The scoring algorithm for a single merge event is defined as:

Score_new = Score_old + {

v_A + v_B if v_A = v_B0 otherwise

Where v represents the numerical value of a tile. The maximum theoretical score depends on the spawn probability of 4s versus 2s.

Reference Data

Tile Value (2ⁿ)	Probability (P)	Color Hex	Points per Merge
2	0.9 (Spawn)	#eee4da	4
4	0.1 (Spawn)	#ede0c8	8
8	Merge Only	#f2b179	16
16	Merge Only	#f59563	32
32	Merge Only	#f67c5f	64
64	Merge Only	#f65e3b	128
128	Merge Only	#edcf72	256
2048	Target	#edc22e	4096

Frequently Asked Questions

The game maps input events to two separate instances. Player 1 controls the left board using WASD keys, while Player 2 controls the right board using the Arrow keys. The input handler listens to the global window object and routes the keycode to the respective game engine.

Yes. The application uses the browser's LocalStorage API to serialize the state (grid configuration and score) of both players after every move. Reloading the page deserializes this data to restore the exact board state.

A deadlock occurs when the 4x4 grid is completely filled and no legal moves exist (no empty cells and no adjacent tiles of the same value). The system detects this state by running a simulation of all 4 directional moves; if all result in a Grid Change = FALSE, the Game Over flag is triggered for that player.

Yes. On touch devices, the screen is split into two touch zones. Swiping inside the Player 1 zone controls Board 1, and swiping in the Player 2 zone controls Board 2. A "Tabletop Mode" is available to rotate the top board for face-to-face play.