Interactive buttons

Here are two easy ways to force the user to "play" each layer. 

• In the Slide Layer Properties, change each layer to a Dialog Layer (Storyline 360: Dialog Layers - Articulate Support ). That automatically prevents the user from interacting with anything on the base. 

or

• In the Slide Layer Properties, select the "Prevent user from clicking on the other layers" checkbox.

Note that you'll need to add a "Close" button to each layer so the user will be able to click items on the base layer again. You could have that appear when the layer's timeline ends.

I suggest that you add the "Line #" text directly to the rectangle shapes. Or use square text boxes with a border and fill for those buttons. That will let you put the triggers on an individual object (instead of a Group). The advantage? You can add a Visited state to an individual object.  Each object would automatically change to Visited when clicked. Then you could have your Continue button change to Normal when all of those objects reach the Visited state. 

If you don't use that method, you'll need to use variables and conditional triggers to track when all of the layers have been visited.

• FYI: This post provides info and a demo about controlling the Next button. The same basic programming works for controlling a custom Next/Continue button: TIP: Controlling the NEXT Button 101 - Articulate Storyline Discussions - E-Learning Heroes