The Goldberg Steam Emulator is an interesting project and one that could be important if Steam ever goes fully offline.
It's a replacement for the Steam API file, allowing you to play a Steam game that uses Steam's multiplayer APIs on a LAN without Steam or an internet connection. Sounds like it's a pretty handy project. Not just if Steam one day vanishes, as it could even help a developer publish outside of Steam, as the developer said:
If you are a game developer and made the mistake of depending too much on the steam api and want to release of version of your game without it and don't want to rewrite your game, this is for you. It is licenced LGPLv3+ so the only source code you need to publish is the source code of this emulator (and only if you make modification to it).
Yesterday, a new release became available with v0.2.5, here's the highlights:
- Inventory support added.
- Initial Steam Networking Sockets implementation (Fixes Hat in Time Multiplayer).
- Updated to sdk 1.46.
- More accurate auth behaviour.
- Leaderboards are now configurable.
- Various remote storage improvements (Fixed saving/loading in a few games).
- A bunch of accuracy improvements and other fixes.
Additionally, that release marked one year since the original announcement (before it was open source). To go with the occasion, the developer put up a blog post. In the post, they go over some issues that have needed fixing for certain games, with some relying on odd behaviour that could easily break and an "overlay" might be coming soon.
You can see more on the GitLab.