Well, I had to release something for the PSP in 2006, here is what I made a few hours after having mine last september.
This was supposed to be a blobby volley clone.
This is unfinished version (labeled beta 0.2), points are not displayed.
Unfortunately I lost the sources of this game, it is coded in C using OSLib, gfx were taken from sourceforge blobby volley 2 project.
Maybe I'll continue it one day to implement wifi for multiplayer and things. Please tell me if you're interested.

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Installation
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1.5 firmware: copy the content of the 1.5 folder into your PSP/GAME folder
1.0, 2.71SE and 3.OE: copy the content of the 1.0 folder into your PSP/GAME or PSP/GAME150 folder depending of your fw settings. 

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usage
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Launch it from game menu
Left+Right : move your blob
X : jump
L : decrease speed
R : increase speed
start : exit to XBM

note that you can't exit with home, hey, this is just beta 0.2 ;)

Hope it'll give you fun

Happy new year 2007!

goebish.