[smirt362]

Well, there needs to be a size limit.
Something like 100 x 100 or 150 x 150 pixels or maybe even smaller. Of course you wouldn't have to use up all that space.

I don't think there should be a color limit, unless someone uses a crazy amount of colors.

I think you should also have to post a zoomed in version of your work as well.

Of course no filters, anti-aliasing, none of that fancy stuff. Just pure pixel art.