Sequence is a very neat idea that suffers from an unfortunate reliance on Grindan to pad out gameplay time (and also a painful overdose of snark.)
Primarily, it's a rhythm game in the vein of Parappa or DDR; arrows scroll down the screen and you use either the d-pad or face buttons (this game almost requires an Xbox 360 pad by the way; you can use other input devices but it was clearly designed for it) to press them as they cross a bar at the bottom in time with some element of the song. But there's also a strong infusion of fantasy-RPG as well; you're juggling three different screens of falling arrows, one of which replenishes your mana so you can cast spells, the second casts the actual spell currently selected, and the third defends against incoming enemy attacks. Your character gains XP after each battle and gains levels and stats; but you also need to use XP to craft new spells, new equippable weapons and armor, and the "keys" necessary to move on to the next floor of the dungeon.
At its core, this is a neat idea and it actually plays really well. Those who aren't very good at ryhthm games might get overwhelmed by juggling three different windows at one time, but the game has a very gentle introduction, and allowing you to level-grind on weaker monsters can give you an eventual buffer in defense so that you can absorb a lot of mistakes. The grinding is also the game's key problem, though; there's just not a lot of content here, so what IS here is repeated far too often. There seems to be only a handful of different songs, all of which are decent, but are repeated for the monsters on each new level (7 levels total.) Each level generally requires a minimum of ten battles to proceed, so you're hearing the same songs and seeing samey button patterns throughout the length of the game.
People tell me the story is actually interesting (I quit about halfway through due to too much Grindan) but it's a little hard to take with the Trying Too Hard humor. It's just non-stop snark in the Cheeto Nerd manner, with a little too much internet meme reference hammered in to boot. In the future I think Iridium would be well-served getting a writer on board who better understands the line between "clever" and "obnoxious."
Sequence ended up being fun to play, but not enough so to keep doing the same things over and over again. I wouldn't mind a follow-up that does a better job of balancing all of its elements. This one is still worth taking a look at for a couple of bucks.