This seems like a cute little casual shooter. I do have a few suggestions though.
- The cats get in the way of fighting enemies a lot. The player can also stand on top of the cats which seemed to cause me to fire over the enemies and miss shots. It might be a good idea to disable physics on the cats or something.
- It is very difficult to hit enemies with the keyboard controls. It might help if the yarn gun had a little bit of a spread.
- While I didn't spend the time to find out, it looked like you could win the game simply by camping out inside the shield around the ship and just grabbing cats that wander by. Maybe the cats should hang out in small areas away from the ship instead of wandering around randomly.