I use transparent links in PowerPoint games and ones for review. I'm adding a link which gives step by step instructions but I want to share a PowerPoint I've already created.
Adding invisible links to multiple choice questions:
Under the Insert menu - add a shape; choose a rectangle.
Draw the Shape over one of the multiple choice or T/F answers.
Right click on the rectangle and select format shape.
Select a color, then drag the transparence line all the way over to 100%. (Make sure there is no line around the rectangle.)
Right click on the transparent rectangle again and select Hyperlink. Click Locate and choose the location of where you want to link to in your PowerPoint. (I've chosen to go to the slide for the correct answer.) Or, you can choose to go to a slide for the wrong answer.)
Test you link and that's it!
I created a slide for the wrong answer and slides to build a snowman as the students get the correct answer. You can create a slide for the correct answer.
Make sure to create a button that links back to the next question from your correct answer or back to the question if the answer is wrong. And, you can copy and past the wrong answer links for multiple choice questions. (since they go to the same wrong answer)
I hope this helps. You'll find many uses for the transparent links.