As you defeat enemies, special particles called Phozons are emitted. These power up your weapon but can also be used to grow plants that produce fruit - which leads us to the other RPG element. As you eat food, your character's HP builds. Collecting Phozons (to improve your weapon) and eating food (to strengthen your character) are the only two means of leveling you have to worry about - it's very streamlined. Beyond that, you have to deal with mixing potions for various effects. It all sounds simple (and it is, separately) but when thrown together on a chaotic battlefield, it's more than enough to engage all of your attention.
Realizing that the conventions of classic games feel clunky 2007, the developers have tempered their love for older titles by making some very appealing changes. When you die, you can jump right back into the action - from the start of the battle that killed you, meaning the challenge is preserved. You can also duck out of the dungeon you're in at any time to shop and save - you'll just have to start it over. These "dungeons" are really just interlocked series of battles, so you won't get bored backtracking. Odin Sphere has all of the convenience of a contemporary game without throwing away its responsive, speedy gameplay.
It has to be said again - this game is absolutely beautiful. It puts paid to the prejudice against 2D gaming we've seen arise in the last few years, with a storybook elegance and beauty that - let's face it - looks better than a lot of the sloppy, so-called "next generation" games we're seeing on newer systems. The classically inflected soundtrack - by the same composer chosen for Final Fantasy XII - underpins the drama and action beautifully.