I'm working on adding new level themes. Right now I have most of the graphics done for a few themes: grasslands, dungeon, city, desert, factory, and space. I'll upload a few preview images to show the progress on those.
I'm absolutely terrible at creating music, but luckily I have a friend who is very talented and -- most importantly -- willing to help me :p. We already have the music created for the main menu, and the grasslands, factory, desert, dungeon, and space themes. The sound effects are pretty crude at the moment (because I made them myself), but those should be a lot easier to create/fix than entire songs.
I'm also wanting to revamp the look of the main character sprite to be an actual cat with actual legs, instead of just a ball-shaped cat that has to roll across its face to move anywhere. I'm not sure if this will make it in the next update or not, because I'm not sure how easy it is to get spriter data imported into unity.