Yes - you're right about the clouds. Very simple, but I like the added randomness.
Thanks for the comments and suggestions! I didn't quite have time to come up with some kind of score idea, but perhaps just a simple monster kill count would be good. And I like the idea of having the butterfly have more interactions - I wanted to add some sort of power-ups that would spawn high in the sky so the player would have to decide if they had time to abandon the guy to get a power-up. Ultimately there are many ideas I didn't have time to implement.
Thanks, again, for the words of encouragement!