I am working on a game in unity, and I am making a slow motion system where a player holds down a button and you will slow down time, but only until your bar runs out, I have that part down, but it looks a bit bland, so I want to make it so when I press the button, it will add like a grey overlay around the edges of the camera that fades as it gets closer to the center, how can I accomplish this?
As @iggy said in the comments, I was able to use the vignette post-processing effect to achieve this.