Sunken Ship

[Sinistral Erim]

C & C? It's supposed to be the background for an underwater tetris game... meant to be anime-simple. What do you say?

[Shrub]

This looks great, considering that you're going for a more simple style.
Some texture on the mast, or anything to stop it from looking like a smooth cylinder, and less uniform, would be good.

Think about what a shipwreck would look like - a bit more battered and broken, considering it's crashed, then deteriorated for decades.
I would make the mast slightly more dented or chipped in a few places. The rest of the ship is fine, though - not all shipwrecks are totally destroyed. The mast just stood out as being too perfect, to me.

[Cilein]

Lovely colors, the foreground blue rocks and pink sands could do with an AA color or too between the two shades, the jaggedness between light and dark shades takes from the overall smoothness of the piece as a whole. Some mussels on the boat or mast might work for texture, play with it, you don't want to make it too detailed as you said. The rock poking out of the sand at the bottom left looks a little lonely, maybe another few scattered in the foreground would make its position more natural (it makes the lower right look a tad empty with it and the starfish on the other corner)? Keep it up, nice work so far

[SwapBrain]

I may be wrong, but as it stands, this isn't really pixel-art to me because no attention has really been paid to the individual -pixel level during drawing. The curves are not smooth, everything is kinda blob-y (as if drawn with a 3px circle brush), and (most importantly) I think the piece suffers for this.

Fist, smooth out the curves, then consider AA for the curves to get rid of remaining jaggies, then consider adding some detail to differentiate sand from rock from cloud. Have to make dinner now, but may take a crack at a small edit later to illustrate my points.

[SwapBrain]

I didn't have as much time to work on this as I would like; I hope this edit helps more than hurts. I know you said that you were going for anime, but, just for the record, anime does not (to me) necessarily mean minimalistic or simple, either. I tried to take it farther in rendering than you might, so I apologize. Also, I added 2 colors, mea culpa. If I had more time I would spend it on the sand, which is just sort of scribbled in, for now.

The main points I wanted to communicate were that a small amount of defining shapes and cleaning up outlines could go a long way. Also, especially because you want your style to be cartoon-y, your rocks should be so rocky that they are confrontational about it: "Yeah I'm a rock! Wanna make something of it!?" Your sand should be so sandy that from a block away people are like: "Oh sh- here comes sand again to stir up trouble..."

As it stands with your rendering, one would not be so sure what was what if a section of the picture was pulled out of context.

Three places I would recommend offhand for the kind of feel you are going for to study are The backgrounds for The Little Mermaid, Pinocchio (the underwater scenes, obv.) and Spongebob. All have different, but very effective ways of approaching this environment.

Anyway, not everything I did is perfect, so don't take it as gospel, but rather as a number of suggestions.

Let me know if you have any questions about what I did.

EDIT: Oh, also - I found working with your palette to be most enjoyable - good picks on the colors.

[Twirly]

Okay good things first: the ship looks cool and the line-art is decent overall, the best thing is, like swapbrain said, the palette - it's really cool and easy on the eyes!
But, to put it bluntly I first thought this was a WIP rather than "cartoony-style" and it comes across minimalistic. (well, that's my opinion! :x)
Even if you make more detailed texture you can keep the animeish look you're going for, I think SwapBrain made a great edit to show you that rocks for example aren't just round objects with ligh that shines on them...
rocks have edges and all that...
Same goes for the wood of the ship, I'd really look at wood texture in real life or even games, it helps.
If you don't agree with all that and even if you do, I think some AA would be necessary
Peace.