I really loved the idea of a tetris based puzzle. The execution was good too. Only thing I would love is a restart level or like a restart button in general. Had me refreshing the browser everytime to finish up the game :)
I Really loved the concept of the game ! I would love to mention a few things like adding a visual indicator of where the enemy is coming from or a sound cue to know where it's spawning can help a lot. Maybe a mouse sensitivity modifier could also help a lot