The level of the game is getting harder once passed Chapter 2. The game makes you to think how to fight the way out, such as changing the parts and the weapons, and of course, need to pratice more to inprove the play skills. Overall, the game gives you so many verarities of combinations to build your own AP, fighting style, out fit, etc....
About the story, it brings the player to another level. Something that never think of. How AI can do, how a living being transforms to another kind of being. Interesting.