One of the most innovative entries I have seen in this jam!
As a puzzle game fan, I am impressed by the twist you put to the Tetris formula. The graphics are simple but effective, and the controls are responsive and easy to use. If you decide to continue with this game, I suggest adding more game feel and game juice to make clearing lines more satisfying.
A minor issue I have is that I think you should not allow the player to put blocks down the edge of the play field. It causes issues when you rotate the board and it blocks the spawning point of the blocks. Besides, it adds to the mechanic of the game if the player is forced to connect ever block to the center of the board.
Good job! I enjoyed your game.
P.S. I invite you to try and give feedback to our game as well! https://itch.io/jam/gmtk-2018/rate/300343