This is a game that is well worth playing. I've played the flash version, and the PSP download looks amazing. I'll get it soon. It's not just a game, it's aquatic relaxation.
Play as any of five aquatic micro-organisms (PS3/PSP). Swim. Eat. Grow. Transform. This is a very simple, yet addicting game that becomes very hypnotic. You won't even be able to keep track of how long you've been playing.
Here is the original flash game developed by Jenova Chen. Simply move your mouse and click to speed up. The creature does the actuall eating itself. Eat the glowing circles and what ever happens to be floating around on your level, but the red circles make you go down a level (made visible by the slight darkening of the screen each time) and the blue circles make you go down. You can eat other creature's glowing circles (which will kill them it you eat them all) but some other creatures will try to eat yours as well, so don't feel bad. It's really not frustrating or challenging (not very).
http://intihuatani.usc.edu/cloud/flowing/Here is the new PSP download of the game, with spruced up visuals and new content (this is where the five different creatures bit comes it), well worth the five dollars it takes to get it, from what I here. It is also available for the PS3.
http://www.us.playstation.com/PSP/Games/flOwThe game automatically adjusts itself to fit your skill level, which is something so totally uncommon. The PS3/PSP game is only available at us.playstation.com, and only downloadable. You can't find this in any store.
Enjoy.