You should only download game files if you own a physical copy of the game. Look for "Ben 10 Ultimate Alien Cosmic Destruction PSP ISO" on reputable ROM archival sites.
To play the game, you need the "ISO" or "CSO" file of Ben 10 Ultimate Alien: Cosmic Destruction .
A balanced mix of beat-'em-up action and environmental puzzles that require specific alien abilities to solve. How to Play on Android: The PSP Emulation Method