In the game Threes!, the “game over” condition is triggered under specific circumstances that signify the end of gameplay. The primary scenario occurs when the entire 4×4 grid, which consists of 16 individual spaces, becomes entirely filled with tiles. At this point, if no further moves can be made—meaning there are neither available spaces to slide tiles into nor valid merges that can be executed—the game concludes.

During gameplay, players manipulate numbered tiles by sliding them across the grid in four possible directions: left, right, up, or down. The goal is to combine adjacent tiles by merging them based on their values—specifically, players can combine tiles numbered 1 and 2 to create a 3, and subsequently, merge additional tiles that are multiples of three to create larger values. This mechanic is crucial for creating space and fostering continued play; however, if the grid fills up and no merges or moves can be executed, the gameplay comes to an automatic end.

Additionally, there exists a special condition that can also trigger a game over: if the player successfully combines two of the highest-level tiles (the 6,144 tiles), the game immediately ends and the player unlocks a 13th character, regardless of whether any moves remain available on the board.

In summary, the core “game over” state in Threes! is reached when the grid is completely occupied with tiles, and the player finds themselves unable to make any valid moves or merges, culminating in the calculation of their score based on the values present on the grid.