The first thing that came to mind when I read the title of the thread was Cave Story. It's good to know my instincts haven't failed me yet...
Anyway, it looks great so far, although you really should add some other enemies to the level, like the hopping cockroaches for example. Also, realize that you won't be able to do much with the four or so sprites Sonikku released, so you better have some other plans up your sleeves...
On the topic of Cave Story, if you're having trouble with Ballos I suggest using the Nemesis for the first two phases, and the rocket launcher for the last two... And if you have the Life Pot, use it...
And yes, I realize nobody ever posts here. I think it's because of me...I don't know why, but whenever I post in a thread, nobody ever posts in it after me... Maybe I am just so awesome that the other people aren't needed.
Good luck with whatever you're doing next.