Since I'm not good at coding and didn't have much time (and energy to be honest) to work on the game it took me approx 2 years, weekends mostly. I guess that if I wasn't studying at medical school and I had a good plan and stayed motivated all the time and stuff it would take me much much less time (six months maybe). I was using Unity Engine and Blender 3D for the 3D things, Gimp and Krita for 2D and Audacity for sound design and music editing.