The arcade classic Pac-Man is a game of patterns. The ghosts move in predefined patterns, so if you move Pac-Man himself in one of three (fairly complex) patterns, it's possible to avoid the ghosts and play the game almost indefinitely -- at least until you hit the Level 256 "kill screen" or you make a tiny mistake and hit a ghost. (On the higher levels, ghosts also no longer become edible after eating power pellets -- though they do reverse direction. This makes things a lot harder.) In this video, Steve Piers explains the relevant patterns, in case you want to become really, really good at Pac-Man:
To go a bit deeper, Ms. Pac-Man was supposed to be harder, with sophisticated randomized ghost movement that couldn't be beaten by simple pattern play. Ms. Pac-Man players relied on a strategy called "grouping," in which you'd "hold" Ms. Pac-Man in a defined location on the board until ghosts converged, then gobble them all up. This was great, except there didn't seem to be a "hold" position on one of the boards. But after a five-day playing binge, a group of players discovered a strategy to achieve extremely high scores, effectively discovering a previously unknown "hold" position. For way, way more on that, read this article on the "Bozeman, Montana Think Tank," the players who advanced Ms. Pac-Man strategy to new heights.