>That would work and make a lot less work for the admin.

OK. The script puts cards randomly.

>I'd like there to be no limit on the number of pics that can be used in the contest,

Sure.

>so if an admin wanted to have 30 or 40 pics, meaning he would have to have 15 or 20 prizes to give out, or even more if they choose.  Is that possible?

I'm not sure I understand it correctly. But let's leave the prize things for a later time.

>If so maybe we do like we have in the pick-a-box contest where they can specify the size of the play area, if that is possible can it be % instead of pixels so it is responsive, unless pixels can be made responsive?

Your question implies that you want to display the play area of the game in the ajax way(note: pick-a-box uses ajax).
Are you sure that's the way you want it?

Basically, there are two ways to display the play area.

(Methid 1) Ajax

The pick-a-box script uses ajax to display the play area. A good thing about ajax is that you can embed the play area in another web page.

(Method 2) Full Page

The make-my-contest script and the christmas tree script use a full page to display the play area. You access the play area by entering a URL. For example,

http://www.make-my-maching-pairs.com/johns-20210-christmas-game

The general format of URLs is:
http://www.(site-name).com/(contest-name)

A good thing about the full page method is that the programmer(me) have much better control on how it looks on differnt platforms(e.g destop computer, smart phone). In the case of the ajax method, the programmer does not have any control on the page where the play area is embeded on. So there are limits on the control of the appearance. For branding, the full page method is better than the ajax method.

So, which one would you choose, "Ajax" or "Full Page"?