Thanks for the feedback, pirate! A slight delay before slurping up a bubble or bumping a crate is probably a good idea. I'm sure I'll do some more with BUB at some point, so I'll keep that in mind. It's tricky to put stuff in exactly easiest-to-hardest order, but you're right, 12-4 isn't terribly devious. :^)
Defining your own sprites and animations isn't as scary as it seems at first. Take a look at BUB for some reasonably-clear examples: 83DXN3L4
Read up on the SPDEF and SPANIM commands; both have a variety of ways to define and animate sprites. My BUB game uses a DATA block to define them and inline SPANIM commands using "I" to determine which frame is shown for how long etc.
Thank you all for your feedback -- I'm so happy you enjoy it! Kl'Dck Hul is right, I originally made BUB for the Gamebuino. :^) I'll have to look into that Ogiri contest. Thanks everyone!