There was a guy who got annoyed because it wasn't free and complied and released a version. The paid one from Dave register is the official release and much more likely to be updated.
The paid one is well worth the small amount you have to pay for it.
The Android version finally went live on the Play Store last summer.
Since then, there have been about 8 updates.
It is now quite stable.
I use a combination of BSB (KAP) raster charts, CM93 (CMAP) vector charts and a load that I've georeferenced myself.
All the charts "quilt" themselves as onto the screen required - even a mixture of raster and vector charts at the same time.
The most recent ones that I've done myself are based on images from Google Maps Satellite.
The idea is that you can zoom right into a bay and see the sea bed.
Then simply switch back and forth to actual charts.
In fact, the paid Android version has a switch to Google Satellite images as standard but it needs an internet connection so might not be much good at anchor.
My Google charts are stored within the Android device and also show waypoints, tracks and the ships position.
Here are some screen dumps - Ibiza - showing the idea.
Note these screen dumps are from the Windows version - OpenCPN will run on Windows, MAC, lots of flavors of Linus and now the Android.
On the boat, I've installed a ships PC which feeds its display everywhere.
Hence my database of charts is common across all my devices.
Note also the purple lines are previous tracks.
