- Looks more like zero mission to me : o -

My counter in GrafX shows me 37 colors. (I couldn't believe that it is only 21 colors, so I tried, I usually don't do that) Still, I am impressed with the technique! I do not mind bigger palette, it is just for order. It is interesting that your picture works without outer AA, I always fight with that. I think that transparent BG should be ok too.

its same enemy.

That's one vibrant sprite. The colors . . . THE COLORS . . .

 well when I saw this i fought it was christoballs' creature  http://www.pixeljoint.com/pixelart/66114.htm

Looks like it's in Zero Mission style. Shame about all the banding, though!

Edit: Actually, not ZM, but mixed with Fusion and your own touch. I like it! :)

Nice creature!

Very good! I love metroid :)

Maybe you could try a transparent background