Depends on the game.
One file browser.opener that I know about is Sm4shExplorer, just to a quick search of the forums. It allows you to unpack files from Smash Bros. archives, modify them and them re-pack them into archives, and then package the mod into a format compatible with Cafiine with just the click of a button.
If you mean you just want to look at the file structure and what sort of files make up a program, just get a simple dump of the game (psst, try searching for DDD) and browse the folders using your favourite computer.
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Psionic Roshambo:
I wonder if I could recommend that to some emulation devs that perhaps the sound could use some smoothing out to simulate those old TVs
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Xdqwerty:
it says it only works for the original R4, R4i Gold (r4ids.cn), R4iDSN (r4idsn.com) and Acekard R.P.G.
