: A newer, highly efficient compression format now supported by PPSSPP that can save even more space than CSO in some cases. Rip/Repack
Standard PSP games are ripped into files (uncompressed disc images). PPSSPP also supports CSO files, which are compressed ISOs. A typical compression might reduce a 1GB game to 700MB. However, "highly compressed" (ultra/7z/zip) takes this further. ppsspp games highly compressed under 50mb