Corona Labs, the makers of the Lua powered 2D game engine Corona, just launched a Steam plugin named Steamworks. Given that Steam is preeminent store for games on the PC this is a welcome move. This plugin gives access to leaderboards, achievements, user stats, player information and access to the Steam overlay system.
From the release announcement:
This plugin is a bit different than our other game networking plugins. For example, there is no login API. Instead, you must be logged into the Steam client on your computer. The plugin then talks to the Steam client to exchange information with the Steam servers. On macOS, it’s best to set up the Corona Simulator as a Steam app and launch Corona SDK from Steam for maximum support.
Many of the API calls return data immediately, if the data has been cached or is readily available. For instance, if you are getting information about a user and the plugin previously retrieved the data, it is returned to you immediately. However, if the data is not immediately available, and you have set up an event listener for that type of data, an event will trigger the listener and then you can update your local data with the new information.
The plugin is available here.
There is also a new Steamworks example hosted on Github available here.