Convert gg to dds Online: gg2dds

You can use Tom's Editor to easily convert images from
Koala Painter 2, packed .GG to Direct Show Surface .DDS.
Tom's Editor is a free, online image manipulation and converter program.

Go to Tom's Editor

GG

Koala Painter is a Commodore 64 program do edit images. GG images are packed using RLE compression.

DDS

DDS are files invented by Microsoft to be used in games, mostly as textures. Images can be compressed to save space but the compression methods defined by DDS are all very fast in terms of coding and decoding.