In the Core Manager, search for "OpenBOR" in the search bar. Select the "OpenBOR" core from the search results.
OpenBOR is an open-source, multi-platform emulator that specializes in running beat 'em up games. It's based on the original BOR (Beast of Redmond) emulator and has been extensively modified and improved over the years. OpenBOR supports a wide range of beat 'em ups, including classics like Streets of Rage, Final Fight, and Double Dragon. retroarch openbor core install
Launch RetroArch and navigate to the "Settings" menu. From there, select "Core Manager" and then "Update Cores." In the Core Manager, search for "OpenBOR" in the search bar