niiice. I have to say, these things have a sheer nostalgic value for me, they have just the same feel of the old-age TMNT sprites, only turned ISO.
May I ask, are you old enough to have grown with the turtles? I sure did love the stupid fuckers :p
The grittyness is also good, and somehow even though you did this in ISO it doesnt feel rigid, as most pixelers that try this projection angle tend to portray it...good...you already have a bit of a voice. nice.
I like your splinter the most, I cant touch the turltes either because I fear they might lose that nostalgic aspect....the soldiers though, their hips feel disjointed somehow, I think you should make them thinner and perhaps drag em to the left.
your overall shading seems a bit....disoriented I may say, how about you give us some kind of photograph or picture with an ambience and lighting you'd wish you could achieve? I bet we can do something to make the pallete and the shading on these buggers livelier if you do!