Sorry for not updating this thread, had some huge tests in the meantime and therefore didnt continue pixeling.
Seems like I am almost done. Tried adding a person which failed, because of the small size it would need to be.
c+c welcome

Atm the light on the face doesnt make much sense when compared to the earths shading. Looks more like a face in front of a picture of the earth.

You seem to have a little problem with tiling there: you are making 24*22 tiles (which is quite odd) and putting them on a 23*21 grid.

this is a small edit showing you how to define the shapes of the stones a bit more. its a very tricky thing to do and you have to be carefull at selecting each shade for the different pixels. actually my try at it isnt perfect either but i hope you can learn something from it

@ Philipptr -  I did but i can't find a reasonable one the all require more time.

Any more fast critics ?

Not true. Changing the palette doesnt take much time. Correcting the angle of the nose, doesnt take much time. Fixing the strange bubbles (I think this was mentioned at pixeljoint) doesnt take much time.

Thanks for the comments and sorry for the late update.
TomF: yes, I thought about ways to create less symmetry after starting to add details too. Actually the scene seemed a bit boring so I tried adding a meteor.

At least the smoke-trails are not symmetric
I will fix the tree tops in the corners when I reach these parts for refining.
Here's the current progress without the meteor if anyone cares:


I didn't have too much time lately, hopefully the progress will speed up again in the next few days.