I want to know more about the game setup and making it playable on different platforms rather than the game.
Is there a tutorial that has a very basic game and how to… for lack of a better word, “Publish”? a game to an OS such as windows?
Uhmm go to build, choose platform and hit build. That’s all there is to it lol.
Now obviously
if(Input.GetKey(KeyCode.W)) Won’t work for Android or IOS, but should work for all computers.
theres also a few up and coming live sessions that are planned.
one for using the UI tools on different devices, and one for converting the Space Shooter tutorial to mobile platforms.
might be info in these that would help.
good content on these live sessions as you get to watch/learn and ask questions related to the session topic if theres something specific you would like to know 
have a look see at the planned sessions and the brill archived content, helped me alot…
http://unity3d.com/learn/live-training