This is a port for Switch of Reicast, a Sega Dreamcast emulator. It's an app that allows you to play your Dreamcast games on your computer or android phone. We've even baked in some magic to make things looks prettier than they did on the Dreamcast. Of course, not all games work, and the ones that do often have glitches
Naturally, there are many other Dreamcast emulation projects, each with its own goals and priorities. Here's a non-exaustive list: Makaron, Demul, Redream, nullDC. If Reicast doesn't work for you, you may want to check these out.