I had a lot of fun playing this! The nuke powerup was really impactful and fun to use. On the other hand, the other unique powerups didn't feel as noticeable or powerful, so it might be cool to make them more visually or mechanically distinct.
There is actually only 20% chance of getting a nuke or the gravity specials, but I think we are getting very lucky and getting the nuke and the gravity block quite often.