Fallout New Vegas looks like this:/ No idea why

imgur.com/vE82lAW

After I install reshade plugins, it was activated and I saw the message on top left corner.
However I can see only half of screen, why does this happen?

My guess is that you downloaded the core package which is mainly for shader developers - you need either Reshade+SweetFX (which contains mainly color modification shaders) or better Reshade Framework (which contains 70+ shaders, including SweetFX, and a configuration GUI called "Mediator")