I think you've chisseled those muscles in there pretty definately haven't ya, looks very un-natural to me imho. It's pretty hard to work at this scale because fitting in all the details you want is almost impossible, just try work on the readability, hint want you're going for and im sure it'll come across much better than trying to hammer every nook and cranny in there.
I've made a little edit if im allowed, not sure whether you'd agree with slight style changes for the character but I just wanted to focus on representing the body to be a tad bit more readable.
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Also altered the palette a tad, trying to make it seem a bit more natural.
Changed the feet too, wasn't sure what this guy is gonna be used for, a platformer? But something is quite ambigious about the whole posture anyway, just needs to loosen up imo.
Oh and I don't think there's need to outline the beard, if anything a shadow to make it more visable but outlining things like that can just seem stuck-on and not apart of the face.