Flycast

Flycast is an emulator for Sega Dreamcast as well as Naomi and Atomiswave, derived from the legendary Reicast (another Dreamcast emulator), which sadly ceased to be active in 2020. This fork, however, is updated pretty regularly to improve its compatibility with the extensive SEGA console catalog as well as the emulator's own features and stability.

This app's compatibility list is incredibly long and covers practically all SEGA Dreamcast and Naomi games. Supported formats include: CHD, CDI, GDI, and CUE, as well as compressed files in ZIP, 7Z, and DAT. It's important to keep in mind that the emulator doesn't support certain titles, including those from SEGA NAOMI 2, Hikaru, and SEGA System SP boards.

As far as the controversial BIOS issue is concerned, they're optional when it comes to playing SEGA Dreamcast games. By default, most of the games work without a problem. You will need BIOS if you want to play Naomi or Atomiswave games, however. Ideally, you create your own backup of any BIOS file you want to update, but if you don't know how, it's possible to find BIOS files and tutorials online.

Flycast is an excellent Dreamcast emulator that lets you play the vast majority of the catalog for what is often regarded as the best console in history, despite ending prematurely, without the recognition it deserved. Now, thanks to this emulator, you can continue playing games on this console whenever and wherever you want.