This concept consists of two things. The most obvious, at a glance, is a refresh to the visual identity that aims to help Steam’s look evolve. Indeed, the intention wasn't to create an entirely new visual style, but to build upon what’s already there to create a more modern look for Valve’s platform.
The second part of the concept is an overhaul of both the Android and iOS Steam apps, as well as a smaller design experiment with Steam’s Big Picture mode. The latter is primarily a means to translate the proposed design language to a different context rather than a proper redesign.
If you're interested in more examples specifically dealing with visual design, by all means look at the Behance project.
Conversely, if you're more interested in the whys and wherefores, you can read my lengthy Medium post about this. It's at least mildly entertaining!