The upcoming MMO BitCraft Online is doing something very unusual for the genre, it's going to be open source. I'll admit, I hadn't actually heard of it at all until someone pointed it out to me on Mastodon. Now, it's clearly on my radar.
It's entering Early Access on June 20th, with support for Windows and macOS. There doesn't seem to be anti-cheat mentioned for it yet, so it will likely work on Linux systems with Valve's Proton. And hey, if the open source it, perhaps community hackers will end up porting it fully to Linux.

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The open source note was written in an official news post back in April, with the developer saying the 3 "foundational reasons" for making it open source:
- We want the genre to be more accessible
- We think BitCraft will benefit from open source collaboration and exploration
- We want to give something back
Part of their work is already open, with SpacetimeDB "an all-in-one backend server and database designed for building and running multiplayer games and apps with incredible speed" already on GitHub.
For the game itself, they haven't noted a license yet, but they did say it will be "one of the OSI's approved open source licenses".