Like y'all, I wanted to see how I could do. Of course, I didn't get all the way to tested code on a gameboy. But it does compress & decompress in Python.

I took the central idea of encoding deltas (or actually delta less 1, since the delta is always at least one; I'll just say delta below), but did it on the full five letter word. The largest delta was still less than 2*18 but bigger than 2*17. (I'm not sure why the blog mentions 20 bits as the biggest delta; I used the dataset from https://github.com/alex1770/wordle/commit/62520406365ca58a1a...)

I decided I wanted a variable length code in bits. Manually, I found the best break-points that I could:

    breaks = [16, 128, 512, 2**12, 2**18] 
    bitprefixes = ['0', '10', '110', '1110', '1111']

So deltas 0..15 are encoded as '0' plus a 4-bit number, deltas 16..271(=16+256-1) as '10' plus a 7-bit number, etc.

Compressed like that, my dictionary runs to 14840 bytes.

    1111000000000001010110 // aahed   4839 =    4839-      0
    1110100001101100       // aalii   2813 =    7652-   4839
    1110110100010010       // aargh   4003 =   11655-   7652
    110011000010           // aarti    339 =   11994-  11655
    1111000000001101110001 // abaca   5634 =   17628-  11994
    00111                  // abaci      8 =   17636-  17628
    00001                  // aback      2 =   17638-  17636
    00111                  // abacs      8 =   17646-  17638
    100111110              // abaft     79 =   17725-  17646
    ...

However, a non byte aligned code isn't ideal, especially on the gameboy's CPU which doesn't have variable bit shifts as far as I recall. Still, over 3000 bytes beckoning to be re-used for some other purpose. Did they put in a soundtrack yet?

Compressor & decompressor: https://gist.github.com/jepler/d502965b57fd52df0838a6def2d32...