Warning, this was a Steam version. Time taken may differ on Android (but is not expected to).
Please note I have only finished a single route (“A New Order”), that's why there is only a red book. The game feature a new game plus mode, as well as postgame features. I also think this game overthrows most, if not every, Exe-Create game thus far.
The short length is understandable, remember there are five ending variations which unlike Exe-Create where each ending is a cutscene, here each story decision actually affects way more than a cutscene. Even if short, I've enjoyed every hour in it; I don't remember enjoying a game so much as Silver Nornir, will probably go after the other endings.
Jesusalva's Rating: 4.9/5.0
Rationale: I kept switching between mouse and keyboard: -0.1 for this!

Definitely worth $ 4.99, at very least. (Unless you like mindless grinding.)
PS. No difficulty settings on this game!