I like your enemies for each area. Well thought out, really liked the Cave part.
The attacking pufferfish, the mantis that shoots sickles at you, so many animal enemies are large and well represented. Unfortunately,i am the year of the dragon, I kind of wish I was cooler like them. LOL. Where is my spread shot? Where is a random heart in the heat of battle? Dragon starts off pretty lame, although I appreciate the mega-man style powers.
The enemy bullets are a little hard to see on certain backgrounds.