This game has to be used with the EU-GTA exploit and a PSP firmware version v2.5 or 2.6. Changes:

Added pause/resume game (press Start button in your PSP).

Enemies will flip back after 5 seconds.

Slighty improved graphics.

Improved tile”shadows”.

Better map generator code.

“double scroll”in bottom sewer waters.

Program version and title on right screen.

Other minor changes.

http://psp3d.com/showthread.php?t=3127