Чего рыть-то? На сайте Sega Retro всё есть:
Kosinski compression is used to compress the following data types:
● Sonic the Hedgehog - 256x256 block mappings.
● Sonic the Hedgehog 2 - level graphics, block mappings and level layouts.
● Mega CD - SUB-CPU BIOS code and data.
● Phantasy Star IV - Text.
Enigma compression is used to compress:
● Various Mega Drive games, including all Sonic games - plane maps
● Sonic the Hedgehog - 16x16 block mappings, special stage layouts
● Sonic Crackers - 16x16 block mappings, 128x128 block mappings, level layouts
● Knuckles' Chaotix - 16x16 block mappings, 128x128 block mappings, level layouts, plane mappings