Fit piece correctly

1. The collision polygon should always be a little smaller than the piece, this is important:

2. The Image Point 1 should always be set to "Top Left":

3. As your new blue piece is made with 5 imaginary squares, you must type this number in its Tag field in the Animations Editor:

Then, the game works fine: fileport.io/zaYm3FUrp5AA

Since each grid cell is a sprite, you can use this sprite to create grids (boards) as large or as small as you like, and the game will still run fine. This way, you can create different levels, some easier and some more difficult for the player.

construct.net/en/tutorials/tetris-clone-construct-1006/page-3

try this, i used it a long time ago to create a tetris blitz clone and even improve upon the new version thats on mobile store, but i never released... forgot where it was... but was 1 on 1 with blitz tetris from EA as cloning goes, and at its core was this tutorial.

if u follow the tutorial ul understand the concept, is basically offsets over a grid layout. is a bit clunky... and convoluted, considering u can do the same with a array... but this is the simple visual way of doing it with overlays and offsets.