Stacker game- game over if not properly stacked

So I’m modifying this code, and I can’t figure out how to make it so that the only way to progress through the game is for the block the player places to land exactly on top of the block placed previously. Currently, they are able to advance if the block is 1 block to the left or right of the stack.

class SquaresStackGame {

  /*
    The number of points that can be awarded
   */
  int MAX_POINTS = 15;
  int MIN_POINTS = 5;

  /*
    Indicates when the player lose the game
   */
  boolean gameOver = false;

  /*
    The total of points
   */
  int score = 0;

  /*
     The size of the game playing area 
   */
  float MAX_W;
  float MAX_H;
  
  int INITIAL_COL = 3;
  int INITIAL_LINES = 2;

  /*
    Initial number of lines and columns which will change according to the game level
   */
  int _LINES = INITIAL_LINES;
  int _COLUMNS = INITIAL_COL; 

  /*
    The size of each rectangle, which will change according to the number of lines and columns
   */
  float _W;
  float _H;

  /*
    The higest level which someone could reach
   */
  int MAX_LEVEL = 20;

  /*
    Level which will be increased as soon as the user reaches the top
   */
  int level = 1;

  float initialX = 0;
  float initialY = 0;

  /*
     The current line which the rectangle will be moving 
   */
  int MOVING_LINE;

  /*
    The direction of the rectangle movement
   */
  int direction = 1;

  /*
    The matrix of our "squares"(actually rectangles) which size is dinamic
   */
  boolean[][] squares;

  // a workaround to avoid mistakely select multiple times 
  boolean holding = false;

  SquaresStackGame(float w, float h) {
    MAX_W = w;
    MAX_H = h;
    updateMatrix();
  }

  void update() {
    holding = keyPressed && holding;
    if (gameOver) {
      if (keyPressed  && ! holding) {
        restartGame();
        holding = true;
      }
    } 

    int curPos;
    // udpdate the square's position
    // we will not always move the square, the pos update will be faster according to how close user gets to the top
    int levelIncrease = level;
    levelIncrease +=  1 + _LINES - MOVING_LINE;    
    levelIncrease = constrain(levelIncrease, 0, MAX_LEVEL);
    int rate = (int)map(levelIncrease, 1, MAX_LEVEL, FRAME_RATE, FRAME_RATE / 20);
    boolean updatePos = frameCount % rate == 0;
    for (curPos = 0; curPos < _COLUMNS && updatePos; curPos++) { 
      if (squares[curPos][MOVING_LINE]) {       
        if (curPos == 0) {
          direction = 1;
        } else if (curPos == _COLUMNS - 1) {
          direction = -1;
        }
        // update the square matrix
        squares[curPos][MOVING_LINE] = false;
        if (_COLUMNS != 1)
          squares[curPos + direction][MOVING_LINE] = true;
        break;
      }
    }
    // if user press a key, move to the line above
    if (keyPressed && ! holding) {
      checkStack();
      if (MOVING_LINE == 0) {
        level++;
        updateMatrix();
      } else {
        MOVING_LINE--;
        squares[(int)random(_COLUMNS-1)][MOVING_LINE] = true;
      }
      holding = true;
    }
  }
  void drawSquares() {
    for (int x = 0; x < _COLUMNS; x++) {
      for (int y = 0; y < _LINES; y++) {
        if (squares[x][y]) {
       fill(random(0,255), random(0,255), random(0,255));
          rect(initialX + x * _W, initialY + y *_H, _W, _H);
          if (y != _LINES - 1 && y != MOVING_LINE) {
            int leftColumn = x == 0 ? -1 : x - 1; 
            int rightColumn = (x == _COLUMNS - 1) ? -1 : x + 1;
            int line = y + 1;
            if (leftColumn != -1 || rightColumn != -1) {
              fill(255, 255, 255, 255);
              rect(initialX + x * _W, initialY + line *_H, _W, _H);
            }
          }
        }
      }
    }
  }

  void display() {
    drawGrid();
    drawSquares();
    drawTexts();
  }

  void drawGrid() {
    stroke(255);
    for (int x = 0; x < _COLUMNS; x++) {
      for (int y = 0; y < _LINES; y++) {
        fill(255);
        rect(initialX + x * _W, initialY + y * _H, _W, _H);
      }
    }
  }

  void drawTexts() {
    if (gameOver) {
      fill(random(0,255),random(0,255),random(0,255));
      textSize(70);
      text("Game Over!", 375/2, height / 2 );
      textSize(20);   
      fill(random(0,255));      
      text("Press any key to continue", 750/3, height / 2 + 40);
    }
    fill(0, 0, 0);
    textSize(50);
    text("Level: " + level + "\nScore: " + score, 0, 50);
  }

  void updateMatrix() {
    _LINES = level * 2;
    _COLUMNS += level%3 == 0 ? 1: 0;
    squares = new boolean[_COLUMNS][_LINES];
    squares[0][_LINES -1] = true;
    MOVING_LINE = _LINES-1;
    _W = MAX_W / _COLUMNS;
    _H = MAX_H / _LINES;
    initialX = width / 2 -  (_COLUMNS * _W / 2);
    initialY =  10;
  }

  void checkStack() {
    // no need to check at the first line
    if (MOVING_LINE == _LINES-1) {
      return;
    }
    for (int i = 0; i < _COLUMNS; i++) {
      if (squares[i][MOVING_LINE]) {
        int lineToCheck = MOVING_LINE + 1;
        int leftColumn = i == 0 ? -1 : i - 1; 
        int rightColumn = (i == _COLUMNS - 1) ? -1 : i + 1;
        // perfect stack, highest score
        if (squares[i][lineToCheck]) {
          score += MAX_POINTS;
        } else if ((leftColumn != -1 && squares[leftColumn][lineToCheck]) || 
          (rightColumn != -1 && squares[rightColumn][lineToCheck])) {
          score += MIN_POINTS;
        } else {
          gameOver = true;
        }
      }
    }
  }

  void restartGame() {
    level = 1;
    score = 0;
    updateMatrix();
    gameOver = false;
    _COLUMNS = INITIAL_COL; 
    _LINES = INITIAL_LINES; 
  }
  
}

pls. post your code again, using the

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code formatter

Were you able to resolve this issue?

The code you provide is only a single class – if you want more feedback from the forum, could you provide an actual sketch with setup / draw for testing purposes?