this link is a video guide for Phantasy Star Online V1 Private Server on Retro Arch
https://www.youtube.com/watch?v=_Oz9Vsb541INOTE: Don't use Phantasy Star Online V2 you will get a Disconnect, Retroarch only Support V1 only
You can now Play Phantasy Star Online Private server with Retroarch using Flycast Cores
Tools you need can be found at the video description
in case anyone need to know the Args for retroarch for Attract mode
args %file -L cores\flycast_libretro.dll "[romfilename]"
romext .cdi
system Sega Dreamcast