So, as the title read I happened to overstayed my Schengen visa for 6 months does anyone know what the consequences could be. If I wanted to return back to Saudi Arabia.
Immediate consequences are that your exit will be recorded in the Schengen-wide SIS database.
This means that the next time you apply for a Schengen visa (and possibly, for other visas) your application will have to go additional scrutiny and has a high chance of being denied.
As far as Saudi Arabia is concerned - as long as you have a valid visa (or don't need one), you will have no problems entering the country.
Unfortunately each member state is free to enforce their own rules when it comes to sanctions for overstaying. There are stories all over the Internet of heavy fines, jail time, questions ... but in the end no one was denied exit.