Your colors are all over the place. Like, it seems like every single robot has its own color palette, and the result is that the image feels more like a collage- or a deviantart-tier sprite comic- than a coherent singular screen. Heck, even your font is made of different configurations clashing with each other. Fire text, cookiedough text, metal text- pick something and stick to it, I'd say.

Work the title screen as a whole, I'd suggest. Rather than focusing on individual robots, layout the palette and shadows and highlights in big general blobs first, and definitely try to unite the palette a bit more.

Instead of thinking of the pile as a bunch of robots, think of it as one big macro-entity composed of robot-shaped granules? Treat it as a painting, rather than a collage.

Most of this advice is mindset-stuff rather than actual design tips, unfortunately, so I understand if you don't find it that helpful.

@Decroded: Why... Why did China come to mind, specifically Why not Japan? Japan appreciates pixelart way more than China.

@OP: I'm pretty much going to try to restate PixelPiledriver's ideas in my own words here, but:

As far as an all-appealing style goes, I recommend you imitate Call of Duty and Skyrim and make your project in 3d high-resolution. Pixelart, by nature, is already niche; if you want a big, undiscriminating target audience, pixels probably aren't what you're looking for.

To paraphrase your words:

"I want an art style that's cheap (pixelart is cheaper than high-res 3d), that I can draw a lot of very quickly (because I have big plans for my game), which I can animate effortlessly (because animating is boring and hard ), and which is colorful and appeals to everybody (because I want my game to be really popular)!"

Buddy, don't we all. If it were that easy to come up with an aesthetic and style, illustration wouldn't be a job, and neither would animation. There's no one-size-fits-all solution to art, no census will change that. In the end, what you draw has to come from your own preferences and the limitations of your skill. The idea of sacrificing your right to choose your art style in favor of some sort of... democratically-sourced average of all tastes, ought to immediately seem repugnant to anybody who self-identifies as an artist or designer of any kind.

Like, isn't the point of creating something that you can call it your own? Why even make a game if you're not going to individualize it to your own tastes?

So here's my take on the pencil drawing part of this.

The red and blue point out the arm- namely, how it's way too short. Your arms should come down to halfway down your thigh or so, not right at the buttocks. The exaggeration of her legs makes her torso/arms seem really stubby in comparison.

The green is basically the question of 'how do those legs even work'? Since your legs are equal in length, when you bend one of them at an angle you have to compensate by lifting your foot so that the net height is the same. Otherwise, you end up with a drawing which implies that the character has different clearance for each of their legs.

In my paintover there, I shortened the legs a bit and tried to make them seem more dynamic.

Avoid hard outlines within the sprites; use selective outlining to reduce the 'hardness' of the sprite's edges and rely on value and color rather than linework to distinguish between individual parts within a sprite.

In a tiny sprite, you've only got like twenty pixels of clearance. If you want to draw an arm in, that's two pixels you have to spend on the lines. If you want to have things like pants and helmets and arms, you have to spend a lot of your pixel clearance on lineart which you could be spending on value blocks instead.