After waiting nearly two years, Unigine Valley will be finally made publicly available on Thursday. This is now arguably the most beautiful and most demanding OpenGL tech demo that's natively available for Linux.
Features of Unigine Valley 1.0 include sixty-four square kilometers of extremely detailed terrain, dynamic user-controlled environment (day/night and weather effects), extremely deep distance of visibility, seamless terrain streaming, cinematic lens flares, interactive fly/walk modes in the open world, and similar benchmarking capabilities to Unigine Heaven.
Worth noting for Unigine Heaven 4.0 and Unigine Valley 1.0 for Linux users is that the engine will require the use of the proprietary AMD / NVIDIA graphics drivers for now. Unigine Corp developers have migrating their OpenGL renderer to now using an OpenGL Core profile rather than OpenGL Compatibility. Overall, their improved GL renderer is closer to being in strict compliance with the latest OpenGL specification, but as Unigine Corp wrote in an email to me, "it seems to be not very compatible with open source drivers." Unigine Corp isn't doing anything to make their wonderful OpenGL tech demos and game engine not work with the open-source Mesa/Gallium3D drivers, but right now these drivers just come up short. As Mesa betters it support for OpenGL 3.x/4.x, Unigine should work again, but for now it's only the proprietary AMD and NVIDIA drivers due to these open-source driver shortcomings.
Even with the proprietary AMD Catalyst Linux graphics driver, Unigine Valley is a bit demanding. While Valley is in a pre-release state right now, it does a good job stressing AMD's OpenGL stack. Earlier releases of Heaven were notorious under AMD Catalyst due to the driver's shortcomings and now for Valley it looks that way for now... There are some rendering problems when using AMD Catalyst but NVIDIA's Linux driver works great.
Benchmarks of Unigine Valley 1.0 (and Heaven 4.0) will be published on Phoronix on their respective release dates.