private void checkDead(){
		for(int row = 0; row < ROWS; row++){
			for(int col = 0; col < COLS; col++){
				if(board[row][col] == null) return;
				if(checkSurroundingTiles(row, col, board[row][col])){
					return;
				}
			}
		}
		
		dead = true;
		if(score >= highScore) highScore = score;
		setHighScore();
	}