Hi.
I have made a testris game before :
http://www.jinxtergames.com/web-games/tetris/The blocks that are used are actually split into several squares.
in my game it moves before you can see it and then checks if something is hit (wall, other block) it will move back to the previous position.
the movement is always in transition steps of 1.
Then when it can't go further down, it will register to the array. using the x and y transition.
for this you will need to use array maker as it is a lot more flexible as it uses refrences.
for this i used 10 arrays with a length of 22 (the playfield size) and as reference name on the arrays i used 0,1,2,3,4,5,6,7,8,9
array 0 would be the most left vertical row and 9 to most left.
When a tile was dropped it will check the position of each block and use that to reference the array, and set an int value (0 = empty, 1 = color red, 2 is color blue and so on.
then i would check each index from each array to check if there is an empty spot.
index would be the horizontal line.
So for example i would check index 0 from each of the 10 arrays and if all are greater than 1 remove the line.
its quite complex to set this up.
using raycasts can be another option but even then you might need arrays.
Here is a video about arrays :