PSP - Spec me some games

[Fortyseven]

Looking for suggestions for PSP games. Looking for unique titles, puzzle or quick arcade type games. Preferably older (and therefore cheaper) games.

Thanks in advance.

 

[Fortyseven]

Think I will pick up Ratchet and Clank, Daxter and the Metal Slug Anthology.

Looking at that Echochorme, Patapon and LocoRoco. They all look fairly interesting.

I like the idea of a new Space Invaders game, but is it worth the extra money over some arcade pack with it?

EDIT: Will pick up God of War when I am through 1 and 2 on PS2

 

[Fortyseven]

Crisis Core

I am getting that with my console so I am glad to see it recommended.