Tetris

Use arrow keys for movement and 'r' for rotation This is my first project after learning C. It contains control, gravity, collision, and line-clearing logic. I did not add a border as it looked rather ugly. I also did not add scoring because it's currently quite difficult to clear even one line. The program gets very slow whenever it runs the collision detection. I haven't studied how to fix that yet, so I plan to address it later.