This is a great engine, but it'd be better if the other 18 characters were added or if it were explained how to add them (and any other bonuses) yourself.
About the other 18 characters the reason why theres only two is because updating the code might be annoying when i add features later on, i may find a way to counter this sooner or later, as for explaination, this will be added in the bonus1 sprite for 1.3.0!