If you already own the Sticks & Rings game pieces, you can acquire just the two digital games (Counting Town and Shape Builder) by purchasing the Early Math Adventure Bundle.
The Early Math Adventure Bundle can be purchased on PlayOsmo.com, or you can download and purchase the individual games directly from the App Store on your compatible device: 1) Counting Town for iPad or Amazon Fire and 2) Shape Builder for iPad or Amazon Fire.
You can try out all of our paid apps for free for 3 days; here's more information about that.