I spent a day trying to make new 'enemy' types. Although they aren't really enemies, so maybe hazards is a better word. I wanted each one to look different but more importantly to act differently and make the player react in a different way. The first one was a spiky ball which just fell straight downwards, so the player could predict where it would be, and where they needed to be to dodge it. Then I made a goo ball that, when triggered, goes directly towards the player. This mean the player has to actively respond to them, and when there's more than one of them it can get a bit tricky. I also added some floating furniture or random sizes which spin in a predictable way, but don't move position. Next I'm going to try some more random hazards, to make the player have to react more quickly.
One thing I'm not sure about is what the consequences should be for getting hit. At the minute there aren't any, but I could make the level reset after a certain number of lives, or maybe the cat gets points all the time it isn't hit, and loses them when it is. That sounds better to me, because it wouldn't interrupt the flow of the game so much. Not sure how to make score work, or make numbers appear on screen, but I'll try and figure it out maybe.