Glad you enjoyed it!
Not sure what you mean by "All of it" but most of the things (cubicles, keyboards, walls, pillars, glass, cart, etc.) are just basic unity cubes, The chair, monitor, and mug were a free Unity Asset and the Rest and character were just very simple Blender models.
I Spend most of time making the physics controller, that why the gameplay had to be dumbed down a bit.
The way the character works is very simple actually, it's only using custom physics joints, which come default in Unity.
You set a Target rotation, Rotation limits, and then a type of force, be it lerp, liniar etc and it will try to keep that shape :) It's alot of trial and error to get it right. If you click the little ' ? ' in the component you get a instant link to the Unity Docs which explains how it works in detail.