Remember Playkot's Supercity? Game artist Paul Geraskin liked has just started a crowdfunding campaign to support working on a new indie game, inspired by Howard Lovecraft: Road to Providence. As with Supercity, Road to Providence will be created with open source tools: Krita, Blender, and jMonkeyEngine.
Right out of the gate, Renderdoc isn't as useful to Linux users as is Valve's VOGL or other utilities like APITrace. Because, as it stands right now, Renderdoc only targets the Microsoft Direct3D 10/11 graphics API, but support for OpenGL is planned under this open-source Renderdoc. While still targeting D3D11 right now, there is basic build support for Linux of Renderdoc. I imagine in the months ahead it will get much more interesting once there's OpenGL API support and open-source contributors have had their hand at improving the Renderdoc Linux support.
Between stable builds, the developers launch a large number of Beta versions that integrate a lot of new features. Some of the updates are pretty large, if we take into account the first one in the new series, but more intermediary releases only feature a small number of changes.
According to the changelog, the performance of the Steam client in some cases with the Big Picture window out-of-focus or in-game has been improved, especially on the Linux platform.
When it comes to supporting the Linux platform, not many of the large studios out there are even considering investing the time and the resources to make this happen. From time to time we get some news about one small studio that is willing to port its games, but there are very few major ones that are openly talking about it.
Codemasters is one of the largest studios that deal exclusively with racing titles. This is a more recent reorientation, but they had great success with games like Dirt 3, F1 2013, and the Grid series.
A user asked around on the Steam forums if the studio had any plans to release Linux ports, and he got lucky. One of the developers said that Codemasters was looking into it and it's a matter of when, not if.