Wow, never has a Disc Gun felt so dangerous to the player! You did a wonderful job mixing the two games, I loved the way you decided to make the player's movement, the crates and Discs spawning... Congratulations! I also enjoyed seeing the Discs with cute angry faces, they're really funny!
Two things that I think would make it even better would be to drop mines on top of the discs and they exploded and/or being able to put the mines on the walls. Also, the speed that you get pushed away from the walls can be a little too fast. But those are just my opinions, it's a lovely game!