This has less to do with lowspec 3d but :
Celeste has one of the most fucked examples of facial anatomy ever allowed into a finished game. Here are the
most convenient examples. Even more fucked than fish-girl from Assassins Creed 2. This doesn't mean it's not a good character (I'll let someone else make that call) or that she's not well developed in the game (haven't played it except an in-store demo), but what it comes down to in my mind is :
Should we copy the glaring errors of other designers in reproducing their characters? The sort of failure you see with the development of her face is clearly from a lack of skill or perception rather than style or tastes.
My vote is paint the cheeks softer (not soft, just softer) and the brow less deeply. Also overall there's a bluring going on - i think it would work better if you relied on more precise renderings, particularly among the eyes and lips (which should be sharp). This would allow you to soften back other forms which maintaining a good facial construction. As a last thing, I tihnk the whole front-pelvic-region should be lifted on the UV - the belt swings too low to be stylish or functional (just gives the impression of a sunken but round tummy) and the bellybutton is getting stangely extended.
Luckly you have a very effective model so these changes are all cosmetic. Good on you for that
