PacMan Portal is a fan-made game that does exactly what it sounds like: adds portals to Pac-Man. So instead of getting trapped in a corner by those god damn ghosts, you simly lay down a portal on either side of the maze and give yourself an exit opportunity that players of the original never dreamed of.
It was created by Russian programmer Dj_smart, and you can download it by clicking on this link.
This isn't the first classic game to have portals added to it—check out Mari0, which gives the plumber a portal gun so he can really fuck with those koopas. They never see it coming.