Good game but there's a flaw: If you fly around the outer edge the entire time, you will very rarely get hit at all. This makes it way too easy and requires no skill at all to do.
It's definitely possible to take out all of a ninja's letters without killing him. It kind of sucks when they run at you and all their letters are red X's already. Also, I haven't beat the last boss yet because when I jump over him and it asks me to press space, nothing ever happens.
 "Dodge"){kind=icon}
 "Streamline"){kind=icon}
 "Typing Ninja Hunter"){kind=icon}