[imtringued]

If you use JSON in an embedded capacity and you're stingy with your bytes, you can just send arrays as your main document.

There was this one MMO I played, where every packet was just a space separated string, with a fancy variable length number encoding that let them store two digits in a single character.

There is not much difference between

    walk <PlayerId> <x> <y>
    walk 5 100 300

and

    ['walk', '<PlayerId>', '<x>', '<y>']
    ['walk', 5, 100, 300]

in terms of bytes and parsing, this is trivial, but it is a standard JSON document and everyone knows JSON, which is a huge win on the developer side.