Sequence is a rhythm game at heart. Where it differs from standard rhythm games is that it features unique RPG elements to mix up the gameplay. Like in a traditional RPG, you'll get into battles with different foes. The battle system is fairly simple. There's 3 windows, all with arrows falling down ranging from left, right, up, and down. You need to press the designated arrows, and if you miss you lose some of your health. One window is to defend from enemy attacks, one is to generate mana, and the last one is to cast spells. It seems complicated at first, but it really isn't. Once you defeat the enemy, the battle is over.
Unfortunately, for me at least. The battle system got boring very quickly. Part of the reason for that is because I found the music very dull and forgettable. But then again, music is different for everyone. So I can't speak for others.
The game also features a story. One which I don't really enjoy... I can't connect to the characters. They try to be funny, but it just doesn't work for me. And the jokes just keep coming and coming. There's voice acting too. Some of the characters sound ok, but others don't. Everything just feels so stale. The characters and backgrounds could use a bit of animation.
I just can't recommend Sequence. There are a lot of better rhythm games out there. The key part of a rhythm game is the music, and I just don't enjoy the music in this game. The battle system gets bland very quickly. Story is optional for this kind of game, but this one tried to have one and it didn't work. I just don't enjoy it.