Usage
More about plugin and API you can read in addons/gd_achievements folder and in wiki
Q/A
How to get branch for Godot 3.x.x ?
Now code for Godot 3.x.x is placed to godot3 branch and you should switch to this if you need it
I have an error "The Identifier "AchievementsManager" is not declared in the current scope"!
Check that "addons/gd-achievements/scripts/achievements_manager.gd" file activated as singleton (check How to install in your project?)
Plugin doesn't work on Android devices
You must add to your exporter .json format for non-resources export:
Export => Click on Android Presets => Go to Resources tab and set .json as filter for resources to export.
Thanks to Dark8Ghost for the found fix