Iwata famously implemented RLE in Pokemon Gold/Silver. That gains an easy 50% from all the whitespace. Huffman coding would be the simplest algorithm to compr

Iwata famously implemented RLE in Pokemon Gold/Silver. That gains an easy 50% from all the whitespace. Huffman coding would be the simplest algorithm to compress the repeated patterns in sprites, but I think even loading up the dictionary to decompress would run into memory limitations on these old systems. If nothing else it would cause hitching.