Fake ports of modern games? Yeah, it's been done before. Same with cart labels. But someone stuck them on actual carts, which will be hilarious once the next yard sale rolls around.
Redbeard Math Pirate on Flickr created 15, spanning the range of cart art on the Atari 2600 - original VCS, second generation, third generation, early Activision, and original Imagic. More of his offerings below:
Yo dawg, I herd you like memes ...
Yeah, and 33-69 is PORN.
I've played this game. It's like Outlaw with multiplayer.
Fake Atari Games [flickr]