Reduce a 27'' monitor for a smaller display?

Just got a brand new Dell SE2717H Monitor. It's a great 27'' monitor, but there's just one thing... I didn't realize how large it was...

This is really an issue for gaming as I have a pretty small desk and I have to sit relatively close to the monitor. I was thinking of shrinking the screen size just for gaming. Think looking at the screen but having the picture in the middle of the screen, surrounded by black space.

I wouldn't mind having black edges on my screen... as long as the game I'm playing would actually fit into my view... right now I have to scan the edges of the screen all the time, which is really a heavy pressure on the eyes.

Do you know how to do that?