TRI wasn't tested on Windows 8. Unity's Linux support is mainly for Ubuntu.
The game also works with Shader Model 2, too, but then you won't get deferred rendering (i.e. a nicer look). From the Unity3D website: "Most graphics cards made after 2004 support deferred lighting, including GeForce FX and later, Radeon X1300 and later, Intel 965 / GMA X3100 and later."
If you have more than one graphics card, like in a modern laptop, allow TRI to use your 3D accelerated graphics card (via the settings of your graphics card vendor)