Settlers II is an absolute classic and Widelands does a pretty good job of carrying the torch. Recently, a huge new update went out in the form of a Release Candidate.
With the current in-progress community development effort to get Easy Anti-Cheat working in the Wine / Proton compatibility layers, they continually hit new milestones.
Destination Sol might not be a name known to all but it's a sweet little space exploration RPG that's free and open source, plus it's getting big updates.
While the Proton compatibility layer already has DXVK for translating DirectX 9/10/11 into Vulkan, VKD3D-Proton has become the official version for translating Direct3D 12 on top of Vulkan.
Up for some more open source gaming fun? Charge Kid, released on June 30 is a platformer that makes you think about your jumps and turns every single one into a puzzle.
FamiStudio, a pretty fun looking program designed for people making chiptune music and NES homebrewers recently had a big new release and it came with their first Linux build.
Monado is the in-development OpenXR runtime for VR / AR on Linux and Collabora continue to make excellent progress on bringing it up to eventually support more platforms and features.
While we already briefly mentioned SDF based real-time global illumination was coming in our post on the recent Godot Engine 3.2.2 release, Godot's Juan Linietsky has now explained the upcoming feature in more detail.
The team behind OpenRA have confirmed their continued commitment to working on the game engine to support Tiberian Dawn, Red Alert and Dune 2000 on modern platforms.
Are your voice chat friends getting bothered by your fancy new loud mechanical keyboard? Or perhaps you're doing an audio recording and need everything in the background to shutup - enter Cadmus.