The game is unfinished. How do I know it? it's made intentionally unbeatable...
Joking, but only partially. 9th chapter is impossible. you have to beat all 9 villains, on ONE HEALTH BAR! No means of healing yourself whatsoever.
And if it wasn't bad enough, there's constantly respawning doppleganger, that follows you and you CAN'T avoid him, because the stage is full of rotating platforms... Which he doesn't activate.
It's basically impossible. It's one of those games., where avoiding damage is a luck based mission. Due to very common issue of outsorcing your programming to the lobotomized monkeys, sometimes enemy's combo still follows you even after you dodged, in impossible manner. Add it to the fact that camera hates you AI isn't affected by it and lack of any kind of balance( Characters that have multi-shooting ranged attacks are just better. It's not matter of different playstyles or tiers... because multishot ranged attacks can just pin you down on wake up and you can just slowly watch your death. ) and you have yourself an adventure.
Unlocking Characters:
Ultraman What's his Face - Face him in W's fourth chapter.
Gundam What's his Face - Face him in Nexus's fourth chapter.
Fourze - Face him in Gundam what's his face (the one in the middle) in fourth chapter.
Or (unconfirmed):
Ultraman What's his Face - Face him in Any Rider's fourth chapter.
Gundam What's his Face - Face him in Any Utlraman's fourth chapter.
Fourze - Face him in any Gundam's fourth chapter.