It is video game console emulator developed by drkllRaziel and Zezu. NullDC is another great dreamcast emulators for PC. If Reicast doesn't work for you, you may want to check these out. Here's a non-exaustive list: Makaron, Demul, Redream, nullDC.
Naturally, there are many other Dreamcast emulation projects, each with its own goals and priorities.
Development traces back to late 2003 and has been largely non-continuous. We work on it in our spare time, because we love working on complicated, headache-inducing projects. Reicast primarily aims for speed and to run on android. Of course, not all games work, and the ones that do often have glitches We've even baked in some magic to make things looks prettier than they did on the Dreamcast. It's an app that allows you to play your Dreamcast games on your computer or android phone. Interested? Head over to downloads and read the user guide NullDC requires DirectX 9.0c, Visual C runtime libraries and optionally WinPcap for modem emulation. NullDC is an open source Sega Dreamcast and NAOMI emulator for Windows, developed by drk Raziel (currently under the nickname skmp) and ZeZu. Games of the caliber of Shenmue, Crazy Taxi, Marvel Vs Capcom 2, Soul Calibur, Jet Set Radio, and Dynamite Cop are just some of the titles you can enjoy with NullDC. NullDC is a Dreamcast emulator, the last console to be released by SEGA, and which all these years later is still considered one of the best consoles ever.