Patch updates?

I was wondering if I released a game how would patch updates work? Would it simply be server based where new files would be downloaded and placed into a certain spot? Or does unity not support this type of thing? So for example I release my game ( which is an offline game by the way ) and there's a simple bug with a part of the game that needs fixing. I'm just worried that the patch update might erase their saved data as well which would be bad. Has anyone done this before with unity?

 

There is no built-in support for that, you will need to create it or use some 3rd party system. There are some on the asset store I believe.