A simple pathtracer renderer I have written (in C++ with GLM and FreeImage libraries) for Advanced Computer Graphics college classes. It supports purely diffuse surfaces and specular ones (with Phong lighting). Geometry culling also works. Parallel computing was made possible thanks to OpenMP.
What you see is a product of the renderer set to 1024 samples for supersampling and 5 reflections at 640×640 camera resolution. Only back wall and floor have specular reflections enabled, all the rest are diffuse surfaces.
For the included image, the render time was a little bit more than an hour on Ryzen R5 1600.