Course advancement

Hi All

Can anyone help me please, I want to use Menu Bar in my courses. I create very large courses. I would like learners to flick through the Menu to different subjects so they don't have to do it in the order I have set out.

However I don't want them to be able to just move to the last slide click finish and that's it.

I would like it so they have to visit all before they can finish the course but also pick up where they left off, if they don't complete  it. 

Can Anyone help please. I think its going to be all visited trigger on last slide or a true or false which i am not very familiar with... and some way of having the bits they have done not available again.

Thanks in Advance....