Unity plus

Now when we spawn a block we want to make user able to controll that shape(left, right, rotate, fall down faster).
But each time we want to move left or right or even to rotate block we will need to check will it hit something.
In update function:

void Update(){
        if(spawn && shapes.Count == 4){ //If there is block

//Get spawned blocks positions
Vector3 a = shapes[0].transform.position;
Vector3 b = shapes[1].transform.position; 
Vector3 d = shapes[2].transform.position;
Vector3 c = shapes[3].transform.position;


if(Input.GetKeyDown(KeyCode.LeftArrow)){//Move left
    if(CheckUserMove(a,b,c,d,true)){//Check if we can move it left
        a.x-=1;
        b.x-=1;
        c.x-=1;
        d.x-=1;
        
        pivot.transform.position = new Vector3(pivot.transform.position.x-1, pivot.transform.position.y, pivot.transform.position.z);
        
        shapes[0].transform.position = a;
        shapes[1].transform.position = b; 
        shapes[2].transform.position = c; 
        shapes[3].transform.position = d; 
    }
    
    
    
}
if(Input.GetKeyDown(KeyCode.RightArrow)){//Move right
    if(CheckUserMove(a,b,c,d,false)){//Check if we can move it right
        a.x+=1;
        b.x+=1;
        c.x+=1;
        d.x+=1;
        
        pivot.transform.position = new Vector3(pivot.transform.position.x+1, pivot.transform.position.y, pivot.transform.position.z);
        
        shapes[0].transform.position = a;
        shapes[1].transform.position = b; 
        shapes[2].transform.position = c; 
        shapes[3].transform.position = d; 
        
        
    }
}

if(Input.GetKey(KeyCode.DownArrow)){
    //Move down fast
    moveDown();
}

CheckUserMove function:

bool CheckUserMove(Vector3 a, Vector3 b, Vector3 c, Vector3 d, bool dir){
    //Check, if we move a block left/right will it hit something
    if(dir){//Left
        if(board[Mathf.RoundToInt(a.x-1),Mathf.RoundToInt(a.y)]==1 || board[Mathf.RoundToInt(b.x-1),Mathf.RoundToInt(b.y)]==1 || board[Mathf.RoundToInt(c.x-1),Mathf.RoundToInt(c.y)]==1 || board[Mathf.RoundToInt(d.x-1),Mathf.RoundToInt(d.y)]==1){
            return false;
        }
    }
    else{//Right
        if(board[Mathf.RoundToInt(a.x+1),Mathf.RoundToInt(a.y)]==1 || board[Mathf.RoundToInt(b.x+1),Mathf.RoundToInt(b.y)]==1 || board[Mathf.RoundToInt(c.x+1),Mathf.RoundToInt(c.y)]==1 || board[Mathf.RoundToInt(d.x+1),Mathf.RoundToInt(d.y)]==1){
            return false;
        }
    }
    return true;
}

So when user press left arrow or right it will first check if CheckUserMove returns true, which means that we can move shape left or right. Also when user press down arrow it will call function moveDown so it goes faster...

if(Input.GetKeyDown(KeyCode.Space)){
    //Rotate
    Rotate(shapes[0].transform,shapes[1].transform,shapes[2].transform,shapes[3].transform);
    
}

void Rotate(Transform a, Transform b, Transform c, Transform d){
    
    
    //Set parent to pivot so we can rotate
    a.parent = pivot.transform;
    b.parent = pivot.transform;
    c.parent = pivot.transform;
    d.parent = pivot.transform;
    
    currentRot +=90;//Add rotation
    if(currentRot==360){ //Reset rotation
        currentRot = 0;
    }
    
    pivot.transform.localEulerAngles = new Vector3(0,0,currentRot);
    
    a.parent = null;
    b.parent = null;
    c.parent = null;
    d.parent = null;
    
    if(CheckRotate(a.position,b.position,c.position,d.position) == false){
        //Set parent to pivot so we can rotate
        a.parent = pivot.transform;
        b.parent = pivot.transform;
        c.parent = pivot.transform;
        d.parent = pivot.transform;
        
        currentRot-=90;
        pivot.transform.localEulerAngles = new Vector3(0,0,currentRot);
        
        a.parent = null;
        b.parent = null;
        c.parent = null;
        d.parent = null;
    }
} 


bool CheckRotate(Vector3 a, Vector3 b, Vector3 c, Vector3 d){
    if(Mathf.RoundToInt(a.x)<board.GetLength(0)-1){//Check if block is in board
        if(board[Mathf.RoundToInt(a.x),Mathf.RoundToInt(a.y)]==1){
            //If rotated block hit any other block or edge, after rotation
            return false; //Rotate in default position - previous
        }
    }
    else{//If the block is not in the board
        return false;//Do not rotate
    }
    if(Mathf.RoundToInt(b.x)<board.GetLength(0)-1){
        if(board[Mathf.RoundToInt(b.x),Mathf.RoundToInt(b.y)]==1){
            return false; 
        }
    }
    else{
        return false;
    }
    if(Mathf.RoundToInt(c.x)<board.GetLength(0)-1){
        if(board[Mathf.RoundToInt(c.x),Mathf.RoundToInt(c.y)]==1){
            
            return false; 
        }
    }
    else{
        return false;
    }
    if(Mathf.RoundToInt(d.x)<board.GetLength(0)-1){
        if(board[Mathf.RoundToInt(d.x),Mathf.RoundToInt(d.y)]==1){
            
            return false;
        }
    }
    else{
        return false;
    }
    
    return true; //We can rotate
}

Now when you press space you should see shape rotate by 90 deegres.

//Check specific row for match
void checkRow(int y){
    
    GameObject[] blocks = GameObject.FindGameObjectsWithTag("Block"); //All blocks in the scene
    int count = 0; //Blocks found in a row
    
    for(int x=1; x<board.GetLength(0)-1; x++){//Go through each block on this height
        if(board[x,y]==1){//If there is any block at this position
            count++;//We found +1 block
        }
    }
    
    
    if(y==gameOverHeight && count>0){//If the current height is game over height, and there is more than 0 block, then game over
        Debug.LogWarning("Game over");
        gameOver = true;
    }
    
    if(count==10){//The row is full
        //Start from bottom of the board(withouth edge and block spawn space)
        for(int cy=y; cy<board.GetLength(1)-3; cy++){
            for(int cx=1; cx<board.GetLength(0)-1; cx++){
                foreach(GameObject go in blocks){
                    
                    int height = Mathf.RoundToInt(go.transform.position.y);
                    int xPos = Mathf.RoundToInt(go.transform.position.x);
                    
                    if(xPos == cx && height == cy){
                        
                        if(height == y){//The row we need to destroy
                            board[xPos,height] = 0;//Set empty space
                            Destroy(go.gameObject);
                        }
                        else if(height > y){
                            board[xPos,height] = 0;//Set old position to empty
                            board[xPos,height-1] = 1;//Set new position 
                            go.transform.position = new Vector3(xPos, height-1, go.transform.position.z);//Move block down
                        }
                    }
                }
            }
        }
        checkRow(y); //We moved blocks down, check again this row
    }
    else if(y+1<board.GetLength(1)-3){
        checkRow(y+1); //Check row above this
    }
}

We will also need to call this in moveDown function when the shape hit something.

else{
    //We hit something. Stop and mark current shape location as filled in board, also destroy last pivot gameobject
    
    
    Destroy(pivot.gameObject); //Destroy pivot
    
    //Set ID in board
    board[Mathf.RoundToInt(a.x),Mathf.RoundToInt(a.y)]=1;
    board[Mathf.RoundToInt(b.x),Mathf.RoundToInt(b.y)]=1;
    board[Mathf.RoundToInt(c.x),Mathf.RoundToInt(c.y)]=1;
    board[Mathf.RoundToInt(d.x),Mathf.RoundToInt(d.y)]=1;

    //****************************************************
    checkRow(1); //Check for any match
    checkRow(gameOverHeight); //Check for game over
    //****************************************************

    shapes.Clear(); //Clear spawned blocks from array
    spawn = false; //Spawn a new block
    
    
}

That's it. You should be able to rotate, move shape left and right, speed down. And when the row is full it should clear that row also all blocks above will fall. Feel free to request any tutorial. I hope you enjoyed.
 Full tetris script.

Source code