Martins is right, though. Some games move you along the vectors* at a higher speed than at the "fixed movement speed" of walking in a cardinal direction. It was very apparent in early FPS games with WASD movement. I still run into games where it shows up made in the last 10 years or so. I guess that's a point for the devs if they didn't look at it. (I'm sure loftar considered it.)
*I'm not going into the math here. Vectors get too cumbersome for basic text like we have here.