Alright guys, This may sound like a strange request, but I have my reasons for wanting to do this. Basically, I want to take Play Coin Setter and make it appear to the 3DS as a legit retail game card. Something like Pokémon X, or maybe Mario Kart 7 (if a CARD2 won't work), or possibly Cubic Ninja? Something that would be logical to boot up and quit a minute later. Simply setting the ROM to not show up in activity log doesn't work. It still adds a title to your software library, it's just invisible. Still blatantly obvious you're hacking. So the first thing I tried was using "3DS To CIA Converter v4.1" There's an option in there to unpack and repack ROM files. Since PlayCoinSetter.csu isn't encrypted, I didn't need xorpads to unpack it. I tried a simple mod to start - I let the program unpack the ROM, which gave me a folder for romFS (which is just one tiny file), and exeFS. I replaced banner.bin and icon.bin with the same files from Mario Kart 7. I had used Queno's tool to unpack the MK7 ROM. The icon was the same 14KB, banner was a bit larger since it's animated. I let it repack, and much to my dismay the ROM it gave me didn't work. I put it on my Gateway and it showed a white square rather than the icon I wanted, and it had no title either. Selecting it didn't help either, it didn't show that I inserted a cartridge. And at this point, literally all I changed was the icon and banner. I haven't even touched the ROM title and unique ID yet. Why is this happening? Does anyone know a better way to do it? Picture of broken ROM: http://i.imgur.com/H8Vbpln.jpg Edit: OK, this is strange. I tried simply unpacking and repacking without touching any files, and it has that same problem. I'm pretty certain it isn't encrypted, as when I try to unpack Mario Kart 7 the same way, it doesn't give me any files. I'm using the one from SDK 5.2.2 as found in the Scene pack. I have no idea how RSF files work, but obviously something's getting screwed up. It does extract the exeFS and romFS correctly from PlayCoinSetter.3ds (I just renamed the .csu) but then it completely fails when repacking, even when I don't modify anything. It becomes 128MB instead of 300KB, but I assumed that was intentional.