Sometimes an anticipated game is canceled at the last minute and then leaked to the Internet years later or not localized for your particular region, so in order to play these otherwise lost and denied classics, many people turn to emulating classics consoles on modern PCs.  That's all well and good if you don't mind jumping through a few technical hoops, but if you want to play these games on the original hardware they were meant for... destined for, even!... then you must jump through even more complex technical hoops.  It can be done though.  With the proper tools, it's possible to give a crappy game a ROMectomy and convert those copies of, say, Doom and Madden '92 for the Super NES that are gathering dust into a single actual real functional working Star Fox 2 game pak.  Lucas DeWoody explains the wizardry required over at Games Are Evil.

Of course, you can go the extra mile for the sake of authenticity. Modding a Doom cart to actually play Star Fox 2 is nice and all, but don’t you want it to look authentic alongside your other carts? The plastic of the Doom cartridge is red. If you want it to look authentic to a first party Nintendo cartridge of the era, what you can do is to modify the board inside the plastic cart, then pull that board out and stick it into another random SNES shell, such as one of the endless unused Madden ’92, ’93, ’94, ’95, ’96, or ’97 cartridges floating around (or just spray paint it, but that looks tacky). Now you’ve got to find a template and print yourself a mock sticker for the cartridge. You’re almost done. Lastly, print some box art available over at TheCoverProject and then get yourself a Universal Game Case to put it in. Congratulations! You just brought an unreleased game out of the digital realm and into the physical world.

It's also possible to buy pre-converted game paks for outrageous prices from the shadier corners of the Internet, but like every do-it-yourself project, I'd imagine it's much more satisfying to actually make these custom unreleased/unavailable games yourself.  While there's always the fun aspect of playing the games, there's also the neverending joy of being able to freak people out by casually placing Star Fox 2, F-Zero 2, or other games that should not exist with your traditional copies of Super Mario World and EarthBound.  I hear that while some people are delighted to see a lost game on the shelf, others simply go mad at the notion.