Nice work there, aeonbluestar! Really nice to see some game art around! Nice maps and textures.
I miss some of the deeper cuts and hard edge you have in your sculpt. The lowpoly seems a bit bubblish to me. In your retop you could try to run edge loops along edges to make them pop a bit more, and some of the polygons are a bit stretched, try to make them as square as possible and even sized. If you could have higher resolution in your game model you could get a less jagged silhouette, making it look more like your sculpt.
I had a look at your portfolio, really nice scenes you got there, keep up the work!
Hope this was of any help,