Prevent click-through until all layers have been visited?

There is an old saying in the theater: "Anyone who puts kids or animals on the stage deserves what happens to them." That means that no matter how well-behaved, or well-trained you think they are, at some time they are going to revert to their true nature, and you can only hope it doesn't happen during a performance.  The SL correlation is: "Anyone who uses groups deserves what happens to them." That means that no matter how well-behaved or how well-trained you hope they are, groups don't play nicely with anything, and especially not states, clicking on, and triggers. Sooner or later, you are likely to have problems with them.

 

Pretty much you can use groups, or you can have triggers and states that work, but not both. Especially in your case, where you can use states to indicate that each box has been clicked. Except you can't associate states with groups.

 

So your first step is to ungroup the groups and delete the textboxes. Then, you can click each rectangle and start typing. That will put text on the rectangle that you can edit.  (Or, you can right-click the rectangle and choose Edit text.)

Once that is done, go to the slide settings and enable the Next button.

Then use this trigger:

Then use this one on each Rectangle:

Notice that the state of Rectangle 1 is not checked because it is not changed to Visited by the time this trigger runs. However, you can safely assume rectangle 1 has been clicked. So on every rectangle, the conditions include all the other rectangles except itself.