Orbit makes sprites, apparently.

[Baegal]

The biggest issue I see is that it's a little too busy.
You have an okay amount of colors, but they are distributed so much that you lose readability. You need bigger pixel clusters.

CLUSTER- A pixel cluster is an connected group of pixels of the same color.

Here we have two larger pixel clusters (not counting single pixels).
Note that adjacent pixel clusters with really low contrast can appear like one single cluster.