I started... but this is quite difficult.
IMO it need to change a bit the style...
pixels at low resolution and low colour can't be that "realistic".
need to go the "cartoonish way".
As you may see with the WIP, a few pixels can really give a different result (for the chicken faces) and as it is animation, it is quite hard to keep something that stay looking like frames of the same subject...
Now I understand why many speccy arcade port games went the cartoonish way (Midnight resistance per example)...
because resolution counts, but colours count too... colours are also some sort of resolution to express something.
while having no attributes, mode 1 also has quite a few colours, so if graphics are in low resolution 'like 16x16... ouch) it simply can't be as efficient as true colours...
Also Yellow is quite a bright colour, compaired to Orange per example, so the highlights in white may not work that well, nor the black shadows, but on the other hand, it would need to be verified on a proper CPC cathodic screen...
anyway, on my way.

Also hyper chicken...
So, concerning the body, it's not that much difficult, even the "easiest" part.
the problem lies in the helmet.
transparancy effect can't reasonably be achieved because of the too low resolution, so ditherings simply can't be effective.
I can chosse to simply try some "glassy mirror reflection" thing, but then we would not se the face... how to recognize those are chicken and not any bird ? (hell even drawing the face, it is not even easy to get a chicken face with such few pixels IMO...
a few pixels actually make a large difference between a chicken, an eagle or a parot or whatever...
I also now understand why Head Over heels was such an impressive job.
Anyway, Chicken is my national emblem, I shall not Fail !!!
But any suggestion are welcomed.
Post Edition : i removed the file so no more spoiler.