more powerpoint help

I originally posted this in my first thread, but no one read it, so i'm posting it here instead. But before I ask the question, I shall elaborate.

I'm making a game in Powerpoint. It's a complex game, where you get to move around through mazes and seas. You therefore need to be able to move to every single "square" or grid location not taken up by a "rock", aka wall. In some parts of the game, you need to go around collecting things, and once you have, I would like it so that the image of the thing that you pick up turns invisible for all slides in a set duration of slides, or a map. I was wondering if this is possible, and if so, how?

If the "Thing" you pick up wa a picture inside of a picturebox control on the top of a slide, or on a form, then you could take a look at the API calls TransparentBlt or GdiTransparentBlt to set the background outline of this thing transparent.

Alternatively, you could re-paint the image of the square that this item/thing is found on - i.e. if the floor was black & there's a n item which you pick up off it, the square this image was on should then be turned black.

To do this for a square in every powerpoint slide, you can perform a loop similar to this:

VB Code:

Dim intSlideCounter as integer 
 
For intSlideCounter  = 1 to ActivePresentation.Slides.Count
    ' Code Here
Next intSlideCounter

Then how do I change the image? And couldn't I just change it to a transparent bitmap the same size as the item?