Test it here (WebGL)

Or download the test apk file and test it on your android device

Touch the screen to drop the block. Line up blocks carefully at top of
each other on order to get as much score as possible. Once the stack
collapses the game is over.

It is very easy to setup AdMob ads, just follow these steps:

Go to Assets - > Google Mobile Ads -> Settings and put your app id (from your AdMob console) there.
Open the script "Menus.cs" and put you interstitial ad id on line 52 for android, line 54 for iOS.

Stack Tower - Unity 2D Game With AdMob screenshots