Donkey Kong Country was among the most ambitious, popular and influential of Super Nintendo games. Technically, its big trick was taking animations rendered on Silicon Graphics workstations and putting them on the cartridge to be displayed as SNES sprites.
The cartridge was 32 megabits (4 MB). That was pretty big for a fourth-generation game cartridge, and ROM chips were a significant contributing factor to total cost. If I were the developer, I would have tried very hard to compress the animations, background images and other data on the cartridge, decompressing them into console RAM for use. I'm sure the developers at the time must've thought of it.
What data compression techniques did they use?