Leadwerks the game engine and visual editor that successfully crowdfunded itself to come to Linux has been shown off a bit.
In the latest kickstarter update Josh showed it off:

Currently still very rough, this is Leadwerks on Linux using OpenGL4.
I cannot wait to see if anyone uses this tool to publish games onto Linux, especially with Josh the owner of Leadwerks saying things like:
Seems we have a believer here.
Considering Unity has no Linux editor yet, it's possible people start to sway towards it.
Source
Update: 3D rendering now working!

Josh has stated they are right on schedule for an October beta - Source.
In the latest kickstarter update Josh showed it off:

Currently still very rough, this is Leadwerks on Linux using OpenGL4.
I cannot wait to see if anyone uses this tool to publish games onto Linux, especially with Josh the owner of Leadwerks saying things like:
QuoteLinux has the fastest possible performance for 3D rendering, so it will be interesting to see what we can do with it.
Seems we have a believer here.
Considering Unity has no Linux editor yet, it's possible people start to sway towards it.
Source
Update: 3D rendering now working!

Josh has stated they are right on schedule for an October beta - Source.
I do hope it helps more people fully develop games under Linux, not just run them. Native editors are often overlooked when porting engines.