I play most of the games without knowing much about them. (That's called Blind play.)
So I when played Azure Striker Gunvolt I didn't know much about it's system. It was fun to learn everything by trailer and error... But one feature I didn't notice until reaching the final level is how the Kudos/Song system works.
Those for whom the Muse sings shall turn the tides of battle.
When you get 1000 points, the Muse (Lumen) starts singing for you and you get more score. That's the secret to reach S/S+ rank in the game.
But I didn't know that because the points resets when you get hit, when you accept a checkpoint and when you use a special attack. (Guess how did I play?) So my score was always low.
I really enjoy playing blind.