Looks like the lowpoly intersecting with the high and casting shadows on it - right click on the lowpoly mesh, go to Object Properties in the quad menu bottom right, and turn off "Cast Shadows" in the checkbox list on the right of the properties window.
If you want to work in games, then ideally you would make assets that will be shown in a game engine, and would work in a game. Environment art in game development is a great option, lots to learn and achieve. A demo reel is less used in game development, as people tend to have less patience and don't want to wait even a…
Vertex color isn't cheap - its 32 bits per vertex and can't be shared as readily as texture information. It really only makes sense if you are applying unique information to sparse geometry or have a fixed limit on texture samplers and have run out. For reference, the vertex color data on a 500 triangle mesh is roughly…