No default unity activity overwrite
This plugins allows you to use android native major feature in your Unity3D android game without struggle.

Demo.
Features:
Well written documentaion
AndroidCore:offers major android features make call ,dial number,compose message,compose email,share text and image,open application by package and open facebook,twitter,youtube views by ids.
AlertDialog:Invoke android alert dialog with holo light,holo dark,device default dark,device default light and traditional themes.
Device:Get user device information like Android version name version code,manfacture,device id,device model,security patch information.
Notifications:Show notification with big text style,big picture style,custom icon,custom imageand load big picture from url useful for push notifications..
Flash:Check flash available on user device and enable or disable flash.
Vibrator:Supports both normal and pattern vibration.
Pickers:This class provide date and time picker.
Toast:android toast message with short and long duration.
Android File:Create and read file in device internel storage.
Simple configurations:Add android permissions with few clicks.