There seem to be a custom made version for linux.
https://github.com/onitake/agsteamstub
Don't know which functionality it replicates, but apparently it makes it possible to run steam version of Heroine Quest.
In theory this will also make possible to run any other game that requires AGSteam plugin.
Hi, I'm the author of that plugin.
I apologize for not discussing my intention to write a replacement to the "real" AGSteam beforehand, I wasn't sure how far I would get and if it would actually work out.
It probably would have been better to ask the developers of Heroine's Quest for a Steam-free version instead, but well, I also wanted to learn a bit about programming for AGS myself, so I just went ahead and started replicating the functionality of your plugin.
Since I got everything working quite quickly, I decided to just stuff the code on my github and post a note on the Steam forums. There doesn't seem to be much interest so far, I guess I'm filling a bit of a niche here.
I also posted an update today that stores the statistics and achievements to disk and loads them on startup.
I'm a bit unsure of how to proceed now. Do you think I should rather take the repository down? Or maybe release a binary-only plugin that will only work with Heroine's Quest? Maybe I should ask the developers to make a Linux version lacking Steam integration available on their website... Or is it ok for you if I keep the code publicly available?