I've been buying a lot of bundles recently, I picked up ~20 in July, and Sequence has been one of my favorite pulls thus far.
*NOTE: This review will be fairly biased, as I enjoy dj-ing/mixing electronic dance music.
If you like rhythm games like Tap Tap Revolution, music - in particular the electronic dance music genre, grinding, and crafting, then you will really enjoy this game. Ronald Jenkees
does a lot of the music for the game, and if you like his style then you will love the music found here.
The aesthetics of the game are nice - the artstyle for the characters and backgrounds are well-detailed. The music is very, very good, however, if you do not like the electronic genre, then you may get tired of hearing the music, and this is critical because it is the core of the gameplay and (so far) the variety is not too expansive. You will also grind quite a bit, so you will be hearing the same tracks repeatedly.
The story is decent, nothing too fancy. The voice acting is not bad, and the comedic banter between the main characters is funny at times. There is also some teasing of common RPG elements, which I always find very nice when not overdone.
The controls are easy to familiarize yourself with - you use the WASD keyes and/or the arrow keys in combination with the numbers (spell hotkeys) and Q and E. The tutorial is skip-able but extremely important for understanding the mechanics of the game. The learning curve is moderate to difficult - especially if you are not used to playing rhythm games. I am pretty good at beatmatching by ear, so I tried the 2nd hardest difficulty and had to tone it down a level - my finger dexterity on the keys are still rusty; however, I plan to do a playthrough on the hardest difficulty once I beat the game.
Gameplay is very, very fun if you are interested in the rhythm genre. You have three windows, Defence, Spells, and Mana. Arrow kills will fall in the Defence and Mana windows, and you can swap your active window with the Q and E skills (left and right respectively). If you fail to press an arrow key in the Defence window, you lose health depending on the type of arrow (basic white color = -1 HP, and so forth). If you fail to press an arrow key in the Mana window, there is no effect.
Arrows will only fall in the Spells window when you activate one of your spells with the number hotkeys, however, you must also have enough mana to cast the spell. Failing to press even a single arrow key in the Spells window will cause you to fail in casting it and you will not be refunded your mana. Spells are the way you damage your opponent, and you can also heal yourself. I believe you can only have 4 active spells at a time (you start with 2 slots and unlock more as you progress through the tower).
Between battles, you can craft and equip different items. There are 7 floors in the tower you wake up in, and you are given new crafting recipes as you reach new floors. One item will always give a permanent bonus (ex: +1 to offence), and others can be new spells, armor, or weapons. You can also scrap your items for experience points. When you craft, you have to pay exp. to increase the chance of success (you can even pay lose levels if you want to pay that much exp); if you fail, you are not refunded the exp.
Levelling up is done automatically, you do not have to allocate skill points.
As you progress through the game, monsters will have a unique "guardian ability" for each floor - for example, on the 2nd floor enemies (once per battle) can activate an ability that makes the falling arrow keys fade to invisibility as they reach the lower quarter of your window. Listening to the beat of the music really, really helps because the keystrokes tend to match the beat very well. With enough practice, you can even swap windows freely and continue pressing arrow keys to the beat. There is a craftable item for each floor that allows you to ignore guardian effects (except when you fight the bosses).
Boss battles are fun and the character's are pretty funny. Each boss will use their guardian effect more frequently, and you cannot negate it with the inhibition item.
If you are interested in rhythm games, definitely pick up this fantastic game.