A personal project of mine that I've been working on for years is upgrading the textures for the 2003 game, Legacy of Kain: Defiance. This is a statue that appears in the game. The game asset is under 600 triangles and is basically a picture of an existing statue from somewhere of what looks to be an Archangel. I didn't find the original statue to reference, but recreated it in Zbrush. I projected the details back onto the original model. It can't be altered to mod the shape so far, so only the texture (diffuse only) was upgraded for the final ingame stuff. Using Substance Painter, I was able to bake in a lot of the lighting and overlayed the detail from the normal and AO maps.
Video of my upgrades so far: https://youtu.be/9AFhG5cLbCA