osu!droid is a port (or a remake) of the original game on the Android platform by Pesets. It's been under beta stage for a few months and now released on Google Play.
1.5.10 (January 14, 2014)
Public 1.4.3b (February 18, 2012)
Closed 1.4.2a (March 13, 2012)
Where do I get it?
It is available in both Google Play Store and direct download.
Simply use your favorite barcode scanner app to scan:
Direct link (apk) (1.5.5)
Available here: http://osu.ppy.sh/forum/viewtopic.php?p=1030037 (outdated)