Phoronix does not benchmark <insert game here> because it does not have a benchmark mode for Linux or has a benchmark that is hard to automate. (For source, it is hard to automate I beleive).
These tests use the following opengl levels.
Unigine requires openGL 3.2 (and higher if available)
Xonotic openGL 2.0
Open Arena openGL ES
As you can see, they cover a decent selection of the openGL feature set. Performance improvements (or regressions) detected by these benchmarks are likely to indicate improvements (or regressions) in other games using the same opengl level.
If you want things to change. Please kindly ask game/benchmark developers to create a benchmark of their game engine that can be launched from the command line. Preferably one that is self contained so it can easily be transferred to the test machines.