Some games come in .gg format but are in fact SMS games. Rename the .gg extention to .sms or .bin to fix them.
These games are mostly listed in this page SMSpower-SMS-GG list.
The "Aspect ratio" doesn't do much in PAL mode, that's normal
The "Region" parameter toggle some hardware features that are specific to the different console models.
Some localized games need these modifications to work properly
Each game cartridge comes with a specific mapper, which description is not included in the .gg ou .sms file.
The core has a special logic to automatically determine which mapper needs to be used, but some games make
a good effort to make this logic fail. The "Disable mappers" parameter permits to force the usage
of the most used sega mapper.