I understand you're looking for information regarding a specific game file: Tomb Raider: Underworld for the PSP in a "highly compressed" ISO format, described as "exclusive."
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A complete remake of the original 1996 adventure, optimized for the PSP’s screen. How to Optimize Your PSP ISOs I understand you're looking for information regarding a
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Here are some details about the PSP ISO file:
Custom-made EBOOT files where modders attempt to port the PS2 version to run on PSP hardware via emulation.