Select the button that you want to disappear.
Click 'Slide Show'
Click 'Custom Animation'
Click 'Add Effect'
Choose 'Exit'
You will get a list of options. You want to select 'Disappear'. You may
have to choose 'More Option' from the bottom of the menu.
Once you select 'Disappear', a box with a drop down menu will appear in the
box where all the animation settings are.
Double click this box.
You will get a dialog box that says 'Disappear. It will have 2 tabs:
Effect and Timing.
Choose the 'Timing' Tab.
At the bottom of the 'Timing' tab, there will be a button labelled 'Triggers'
Click the Triggers button. Two more options will appear. Select the radio
button next to the option that says 'Start Effect On Click Of'.
In the drop down box next to this option, select the button you're trying to
make disappear.
I am doing the same thing - making a PowerPoint game. And I've noticed that
if you have text boxes on top of the action button, you have to click on the
edges of the action button in order for it to disappear. Not sure why.
Could just be some quirk of my machine. But just know that.
Hope this helps.