You can download and run the various Unreal Engine 4 demos from here, just replace the zeros with dots: forum0benchmark0pl/topic/125341-unreal-engine-4-realistic-rendering-room-demo-do-pobrania/ I'll use the Elemental Demo as an example: Run the .exe in "\Elemental\WindowsNoEditor\Elemental\Binaries\Win64\" You can change the resolution by navigating to to this location: "\Elemental\WindowsNoEditor\Elemental\Saved\Config\WindowsNoEditor\" And editing "GameUserSettings.ini" Also in-app, you can toggle the console with the ~ key. A useful command is "stat FPS" which displays your FPS count. I'm getting about 20-40 FPS on the Elemental demo with my GTX 670
There are several distinct demos, it's up to you which you want to download and test. For example, download "Realistic Rendering Room", extract it and run the .exe in "*extracted location*\RealisticRenderingPackage\WindowsNoEditor\RealisticRendering\Binaries\Win64\". The .exe location follows the general path: "*extracted location*\*Demo Name*\WindowsNoEditor\*Demo Name*\Binaries\Win64\". Similarly you can generalise the configuration .ini locations. Just download the files using the links directly below the demo titles which are in bold. I would've formatted my original post to include the links and show clearly the demo they relate to, but currently I'm unable to post links.
I looked at the unreal engine. You will need MSVC to compile it under Windows. If you use it in a commercial project, you will have to pay them royalties.