Seeing many of you are still having problems with CD games, here are some detailed instructions:

-First of all, you'll need the Sega CD BIOS. This is the software Sega CD used to operate the CD ROM unit. Since this is complex software, we can't just emulate it. And just like games ROMs, this is proprietary software I can't distribute freely. There are 3 versions of these BIOS: Japan (JP), Europe (EU) and North America (US). If you want to play CD games from all 3 regions, you'll need all 3 files.

US BIOS file must match ONE of these names:
us_scd2_9306.bin
SegaCDBIOS9303.bin
us_scd1_9210.bin

EU BIOS file must match ONE of these names:
eu_mcd2_9306.bin
eu_mcd2_9303.bin
eu_mcd1_9210.bin

JP BIOS file must match ONE of these names:
jp_mcd1_9112.bin
jp_mcd1_9111.bin

They can be individually zipped but the names must be kept (thus us_scd2_9306.bin becomes us_scd2_9306.zip, etc.) Also remember the filesystem is case sensitive.
How to find them? A quick prayer to Saint Google the Miraculous should suffice.
Once you have them, simply put them in /home/user/.picodrive/bios


-In order to play the actual game, it's best to create a new folder and put the game's iso and mp3 files there. Make sure the mp3 files have the same naming pattern of the iso file, followed by a dash/underscore/space and a track number. DO NOT DELETE OR EDIT TRACK NUMBERS. Make sure all files of a game are in the same folder.
Also notice that CD games CAN'T BE ZIPPED. In some rare cases you'll get the game to work, but then you won't have CD music.


-If you've done all this and your game still crashes sending you back to the main menu, recheck every step. Check your BIOS location. Check you have all 3 BIOS files. Check your BIOS names (remember - case sensitive). Make sure you unzipped the game first. Finally, if all this is OK, perhaps your BIOS or ISO files are corrupt.

Hope this helps.