Update: Google Play Store link is now back online. The developers have also clarified that the APK downloadable from Github is not from them.
Custom Android ROMs each have their own highlight characteristics. A prominent feature on Paranoid Android, for example, is Peek, which gives enhanced access to notifications, which are available through motion-detection. For example, simply lifting your smartphone from the table or taking it out from your pocket wakes up the screen, and shows you actionable notifications right from the lockscreen.
In the developer’s own words:
The design philosophy behind peek was to deliver a smartwatch convenience. When you [...]