This game's amazing. Since Buuhan asked…
The gameplay's pretty fun, but it's the RPG mechanics that make it last. The fighting elements are pretty simple; You have a 4 hit combo on the ground and in the air (it's virtually the same attacks.) You also have an aerial attack (which is more useful for some characters than others) and a "critical" attack. Each character has about two unique special moves.
You have a very limited moveset. To get good at the game, you learn the exact shape that your weapon carves in the air for each attack. An added nuance is that holding a direction while you attack makes you jump into that direction during the attack, even when you're mid-air. After you've played a character for a while, you start using this to dodge attacks. Part of me wishes you could upgrade this mechanic by purchasing moves or something, but as is, each character's moveset is very precisely thought out.
You have a pretty wide variety of spells, but most of them don't seem too useful (keep in mind, I haven't played through all of the game, and I've only been able to use two of the 5 characters so far, both of whom are melee characters. I'm expecting that spells are used more frequently for the mage-like characters.)
As for the RPG mechanics - in a way, it's sort of like an RTS. Think Starcraft, except instead of mining crystals, you mine people. Each level consists of a map of circular stages. You can't leave a stage until you defeat all the enemies on it. Defeating enemies yields "Phozons" which you can either absorb into your weapon to gain experience for your Attack stats, or you can plant a seed in the ground. The seed will eat the Phozons, produce fruit, and eating the fruit may cause your HP to level up.
What makes this game really fun is the alchemy system. Here's how it works - through the game, you collect "Materials" which are the bases of all alchemy recipes. They have a number that I think caps at 79 (I might be mistaken, though.) Think of it like an element's number on the periodic table. Once you have the proper recipe, you can make a potion by mixing the proper number Material with the proper ingredient, which is usually one of 5 easily obtained vegetables.
Putting anything else in a Material causes its Material number to go up. All seeds make the number go up by 1. Bones (leftover trash from eating meat) make it go up by 3. Combining two materials multiplies their numbers together - Material 2 and Material 10 makes Material 20. Once you get past 10, the physical properties of the Material loop around - the 'ones' digit defines what recipes it can be used in. So, anything that calls for Material 1 can also use Material 11, Material 31, etc. The difference is, the higher the 'tens' digit, the more Phozons you produce, which is useful for feeding plants or providing instant MP for boss fights.
For any item in your inventory, there's usually at least three things you can do with it. For instance, you know you can use Seeds to make plants which eat Phozons and bear fruit. You could also drop an Egg, feed the hatched chicken the seeds, and the chicken will produce more eggs. Eating the chicken produces a bone which you can use for alchemy. You can use the eggs to hatch more chickens, or you can keep them, and have them cooked at your home base for permanent HP bonuses. And on that note - they can be used in at least 5 different recipes.
The other thing that's pretty amazing is the plot. The actual story isn't too amazing, but the way it's told is genius. Essentially, you play through a single character's storyline. Along the way, they'll meet the other characters, occasionally fighting them, occasionally working together. After you beat a character's main story, you play the next one - seeing the story unfold from his perspective. This game has 5 separate storylines, occurring simultaneously, and intertwined in the frame story of the end of the world.
This game's pretty addicting, but it does get repetitive. There's not a lot of variety in enemies, the stages are structured identically, and to top it all off, you play each level 5 times - once for each character. Who each start at level 1 with no items or equipment, and only after you've beaten another character's main story at level 30. The game is also REALLY hard sometimes. And there's an issue of slowdown, which is surprising considering how low-tech the game is.
Despite that, this game is amazing, and I can't recommend it enough.