This is our first game. We obviously came up with idea while playing and loving 2048 but wanted to build something that is a little bit more difficult. Annulus is different as any time two circles merge, they change the color and hence putting similar circles in any corner strategy won't work.
Thanks for your feedback. We agree that there is always room for improvement. In coming versions, we will be addressing the issues in problem explanations, fixing reported bugs and adding more problems.
Google Play Store hasn't updated the install count since last 48 hours or so. Flurry data is showing about 50 users for paid and about 200 users for lite version (These numbers contain both iOS and Android installs but we are sure that Android downloads are more than 5.
The app can run in offline mode. No internet connection is required.
The only time Internet is required is when you buy it from Google Play and run the application for the first time. Connection is required to validate the purchase with Google servers.