Downloading Nintendo 3DS games is punished by copyright laws.
Please take a look to your country's copyright laws to know if private copying is legal.
If yes, you can use the Sky3DS linker and this piece of software for playing at your games's backup.
The Mac OS X edition is now out!
Sky3DS is a Nintendo 3DS linker, a special game pak with a MicroSD card slot.
So, on that MicroSD card, you can put in 3DS games backup files (only in .3ds format.)
That linker makes for Nintendo 3DS casual developers possible to test the software they have created.
The Sky3DS linker needs a specially formatted MicroSD card.
Then, the Sky3DS Utility will place your 3DS backups in your MicroSD card, and will adress an order number on each game.
Then, you can insert your MicroSD card on the Sky3DS linker slot (Of course, insert too the Sky3DS linker on your 3DS system) and power on.
The Sky3DS hasn't on-screen display, to change the game, please return to the start page of the 3DS system, and press fastly a little bit on the Sky3DS's button.