OctaneRender is a GPU based renderer with plugins available for just about every popular 3D content creation package. Yesterday, they
released a plugin for Unity. This enables you to renderer incredibly detailed movies and cut scenes directly from Unity or export to work directly in Octane Render or another supported application. The plugin is available on a subscription basis, with a free option available but confined to a single GPU. For additional GPU support, as well as access to Octane Cloud servers as well as After Effects and Nuke plugins, it will cost $20 a month. Finally for all of that as well as up to 20 GPU support you pay $60 a month.
You can get started completely free by downloading and installing this scene in Unity. Installation documentation is available here.
I did a video showcasing Octane Render in action available here and embedded below.