Forget your preconceptions about what gravity sensor games are, most of them never got the chance to step out of the device.
Against gravity is a free unique game in its own right, where you have to throw (and catch up) your device in order to score.
While signed in with your Google+ account, you can earn in-game achievements and compare your scores with others playing the same game with their Google+ accounts on different leaderboards. Mulitplayer mode will also be enabled to challenge your friends (or random opponents) in real-time. Your progress will be saved with Cloud Save, so you can pick up where you left off on all your devices.
Note: Don't panic, you will not going to flood your circles with score and achievements notifications. No message are automatically posted in your stream (until Google changes something).
Because Against gravity is in beta, you have to join the respective community and follow the instructions:
Join Against gravity (beta) g+ community
Opt-in as a tester on https://play.google.com/apps/testing/org.quet.android.againstgravity
Thus, you can download and try Against gravity from the Play Store
This game is far from being finished but it can already be played, and I thank you all in advance for reporting bugs and critics which will help to have a stable release.
DISCLAIMER: Of course, I will not be held liable for any damage or loss arising out of or related to your use of this application. And I will not be held responsible for any direct or indirect damage, loss or theft of the personally owned device. Your use of this application is solely at your own risk.