Even though Citra 3DS has been around for a few months, tonight was the first time i heard of this Emulator, which is still in its early stages and the creators still able it a WIP, here is some information about Citra:
Citra is an experimental open-source Nintendo 3DS emulator/debugger written in C++. It is written with portability in mind, with builds actively maintained for Windows, Linux and OS X. Citra only emulates a subset of 3DS hardware, and therefore is generally only useful for running/debugging homebrew applications. At this time, Citra is even able to boot several commercial games! None of these run to a playable state, but we are working every day to advance the project forward.
Here is a video of it showing The Legend of Zelda: Ocarina of Time running:
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