That question wasn't very clear.  
Essentially, I am trying to make a multi-player Pac-Man game whereby the players (when playing as ghosts) can only see a certain radius around them. My best guess for going about this is to have a rectangle which covers the whole maze and then somehow cut out a circle which will be centred on the ghost's rect. However, I am not sure how to do this last part in pygame. 
I'd just like to add if it's even possible in pygame, it would be ideal for the circle to be pixelated and not a smooth circle, but this is not essential.
Any suggestions? Cheers.
The best I can think of is kind of a hack.  Build an image outside pygame that is mostly black with a circle of zero-alpha in the center, then blit that object on top of your ghost character to only see a circle around it.  I hope there is a better way but I do not know what that is.
How do I display a large black rectangle with a moveable transparent circle in pygame?