I picked up Knights in the Nightmare recently alone with Crimson Gem Saga for a bit of portable RPG action. The US release of the game came with a soundtrack and artbook, which showcases some of the excellent illustrations in the game of various characters and Knights. I'm fairly sure this game is getting a Australian/UK release, I've just no idea when and couldn't find a release date. I really didn't know much about this game, it's probably one that might of gone unnoticed if it wasn't for the fact that Atlus sent me an email which piqued my interest., then again they do release awesome game, so you can't really go wrong there.
This is one of those games where you'd try and explain it to someone and in the end just say "no, you're just going to have to play it to understand". The way the whole game controls and plays is something you can't get a good idea of until you've played a battle in it, and even then there is so much insane shit going on in it you need to play another just to grasp what happened the first time around.
I can't compare this game to anything else, I don't feel I've ever played anything like it. However the jist of it is, it's a SRPG based on a grid, however you don't control the Knights but instead control a whisp that can be used to select a weapon for a Knight, select the Knight and then charge an execute an attack. You goal is to fill a 4 x 4 matrix, each enemy killed fills a certain block on this matrix, filling 4 up or down gives you a win. You are given certain amount of turns to fill this grid/matrix, the start of a new turn allows you to select which enemy will appear on the grid, select your Knight and weapons. Oh and you have to do all that while watching your time limit, dodging projectiles which reduce the time limit also and watching your MP which lets your perform the special attacks with weapons. Easy, no?. There are far far more aspect to it, like any SRPG but hopefully you get a general idea.
Regardless it's one of those ridiculously addictive games, similar to Disgaea in that regard. I'm sure I'll be unlocking new weapons and Knights for quite a while yet.