This is pretty, and it's turning out good. But it has a problem that haunts more of your pieces.
Pixel Technically it's greatly done, and there's heaps of detail. But there are alot of structural, form and perspective issues.
One of the main flaws here are the legs of the alien machines. They seem to be connected in such a way that it would make it impossible for them to walk.
There are no joints in between the pieces. Which makes it look rather akward. The perspective of the legs is also very strange.
Another problem is the lasers. They look more like a red plant, rather then a high energy beam. You need to somehow make it clear that these things are indeed what you want them to be.
In my edit, I used a 20% opacity brush to show a glow. Of course you don't have that luxury in the pixel art itsself, but I urge you to try something similair.
The spirals around the lasers are also too random. You seem to kind of have made a combination between static discharge and a spiral, which turns into some random mess.
I think that a more correct looking spiral can help make this move more. Also, a more impressive, more powerful looking impact can probably help make this look more realistic.
Here's a quick overpaint of a few things:
