man this would be easy to turn into pixel art in 5 steps
resize it to a normal pixel art size (using interpolation to automatically do half of your AA work.
desaturate whichever method yields best contrast (in this case it was desaturate luminosity).
drop colors to a reasonable amount (I gave 16).
clean everything up to be pixel perfect.
then reintroduce your colors individually tweaking each to ensure smoothness.
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I did the first 3 steps. The other two steps will take you a long time if you want to have great pixel technique. There are other ways to go about this, such as skipping step 2, but I think step 2 will yield a smoother palette with fewer colors in the long run.
