I think you should pick up a book on perspective, a good one I own is Perspective! For Comic Book Artists by David Chelsea. You should also think your light source(s) more. I think your problems are fundamental though, so you should pick up some fundamental books too and study some more from life, mainly still life. You're young, get the tedious stuff out (though to be honest, I enjoy studying, but it can be a bit over-whelming at times) of the way so you can be creative and know what you're doing!

Interesting little flash game a friend showed me, its pretty cool, Halo 2600, at demake of Halo with Atari-esque gameplay/graphics/sounds: http://www.codemystics.com/halo2600/

Your work is very odd (not in the bad way, its just different, which I enjoy), especially when it comes to faces, are you intending to make your faces more abstract and stylized or do they just usually come out that way? Also are you using reference for your work? I think if you used reference you could be much more convincing with the body of this animal, you could also be more accurate about color. Give this a background, make it a scene, more then a just sprite doodle, it has a lot of potential but of course, every piece anyone makes does, its just up to the person to fulfill it. Also I personally think it looked better before the update, but thats just me.

Its looking good, except I don't think the selout on the arms with the blue is working, along with Shatterhand's jacket is green, or red but never that color.

I really don't think you should up the game's resolution, its gonna be tough doing all the graphics as is.