Today's Free App of the Day is Cubes vs. Spheres
This is a physics-based arcade game. Some reviews compared it to a shoot-em-up, some to Angry Birds. :D It's well reviewed and there don't seem to be any privacy issues. You battle spheres against cubes for as long as you can!
6 of 11 reviews are four stars and above.
These apps are compatible with the original Fire and with my Fire HD 8.9" 4G. To tell if an app works for your Fire HD or other Android device registered to your Amazon account, click on the above link and look on the right side of the web page. Amazon will tell you if it will work with your registered device.
Also check out the other digital deals from Amazon, including great deals on MP3s and videos: