The trailer made Chaos Fighter looked like an interesting game so I downloaded the game right away. The Chaos Fighter trailer even had a character that looked like Saber from Fate/stay Night. Honestly, I kind of got bored with this game about an hour in testing it. For some reason, it wasn't fun at all. There are special features where you can learn hundreds of skills mix and match them with different characters and avatars. There is even an auto leveling feature where you can automatically repeat boss fights over and over. This game seems like a very casual type of RPG. I've already uninstalled the game as it didn't suit my tastes. I suggest skipping out on it, but if you like the style and the auto play features, then try it out!
If you do end up trying the game, you must create an account after patching the game. The registration button is in underneath the login screen. Just click on the one to the right, though it may change in the future, then all you have to do is enter a username and password, leave the last box blank and you're good to go.