Someone I know is working on an RPG Maker game, and wanted to add achievements without the hassle of writing lots of C++ code. Good news is as of Steamworks SDK 1.32, exports have been added so C++ is not necessary to use most of Steamworks. As such, I have created a script that requires no DLLs other than the Steamworks DLL itself.

Here's how to use the script:

• Copy steam_api.dll from the Steamworks SDK to your project root folder. Important: you must use Steamworks SDK 1.48 or above for r7! Check tagged revisions if you need a version for an older SDK version.

• Paste the script into the script editor.

• In an event script or wherever you need it, write the following:

    steam = SteamUserStatsLite.instance
    steam.set_achievement 'YOUR_ACH_ID_HERE'
    steam.update
  

• If that second line returns true, the achievement has been set. Otherwise, you'll want to check if you set up achievements properly on Steam.

Please go to https://gmman.github.io/RGSS_SteamUserStatsLite for documentation.