OK, so basically I was messing around with the contents of my 3DS's SD card. I have done some tests with Kirby's Dream Land, and here;s what I found. Replacing .app files will still allow the game to appear in the menu, but not boot. Editing the CMD still allows the game to boot. I replaced the last 4 digits of Kirby's CMD with HAXX and it still works fine. Swapping TMDs with Zelda DX (A game I don't own) still allows Kirby to boot. This one really baffles me. Any insight on why these things happen? The .app one is obvious, but the later two make me wonder.