it´s not easy, but is possible build a model low poly and with a lot of details that perhaps can possible only in Z-Brush!

If you trying to make low-poly object look like hi-poly, and you know advanced modelling in 3d app like 3ds max, z-brush, mudbox, then u might know, that you can "bake" hipoly geometry on lowpoly mesh.
it's quite simple and easy and produces great results. result of "baking" is often a normal-map or displace map, which cryengine uses well.
i don't see straigh question, but i hope i helped you

google on: "baking hi-poly" or some kind of this

thanks for advice, this models was made when i was learning modeling in 3d max. i know the best way is make a high poly turn into a low poly, it´s a road most short, sure!

while it's true that the best workflow is to make the high poly first and then make the low poly around it, you need to learn the fundamentals of poly modeling first. creating a mesh that gives the boldest silhouette statement with the lowest number of polygons for example.