R4 3DS Emulator can be used for testing how DS games will work on a R4 3DS Flash Card. It can also be used for playing games on PC if you do not have a Nintendo 3DS consoles.
R4 3DS Emulator also known as Nintendo 3DS R4 Flash Card emulator is based on the freeware NDS emulator No$GBA. It mimics the operation of a R4 3DS Flash Card such as R4i 3DS, AceKard 3, SuperCard DSTWO and CycloDS iEvolution on N3DS. Same as current first generation R4 3DS backup tools this emu supports only DS-MODE on Nintendo 3DS. This means that NDS roms and DSi game backup copies work, DS homebrew Apps work, but the new 3DS games are currently not compatible. Support for the latest 3DS games will be added in later versions.