PSN Games?

[LunaMoo]

That's not exactly true. PPSSPP only supports native PSP games/apps which basically means everything except PS1 games as they are using emulator existing on PSP firmware which PPSSPP will never have. All the other non native to PSP games like PC Engine games however are using their own emulator included with each game and those work fine at most will have typical problems to all other emulated games like might not work with texture scaling(but still can be upscaled via 5XBR shader etc).

Such games however come with DLC's where the "game" is just an emulator while the DLC is ROM for that emulator so you have to place the DLC in the correct folder the game wants it to be, otherwise it will not work and your black screen is just emulator not seeing the rom it should have. They cannot work without DLC as of course the DLC is the actual game:].

For example with Gate of Thunder, copy all files from USRDIR and it's subfolder called CONTENT to memstick\PSP\GAME\NPJJ30011, then copy SAVEDATA and SAVEICON folders there as well(some of those might not be needed, but whatever;p, also different games might have different files and not all of those files absolutely have to run from GAME folder, but it's lightweight enough that it doesn't matter really) and boot the game from PSP homebrew/demo tab, note you'll also have to confirm some emulator screens when booting the game and save before you reach the title:
   
   

Here's also an example from Neo Geo game:
   
this for example had only eboot.pbp in content and ISO.BIN.EDAT(which isn't needed), so it can be placed anywhere and it will run, just avoid original folder structure as extracted pkg's end up with folder structrure that PPSSPP will see as a savedata from inside it's file browser.;3