Steamworks API wrapper for Godot Engine (version 3.x)... now for GDNative. Available for the Windows, Linux, and (soon) Mac platforms. It is based on GodotSteam 3.18.3 with Steamworks SDK 1.55.
This version is meant for Godot Engine 3.5, but it may work with previous versions.
Previous versions of the plug-in can be found at the GodotSteam repository: https://github.com/Gramps/GodotSteam/releases.
You can find the full documentation with tutorials at https://godotsteam.com.