Ms. Pac-Man is lauded as one of the greatest games ever made. In case you have missed out on this classic formula, the gameplay is simple. You are Ms. Pac-Man and your job is to eat all the pellets in the maze you are in. You have to avoid ghosts that chase you. However, large pellets you eat will allow you to turn the tables and also devour the ghosts for a short time. The object is just to get as high a score as you can / advance to the highest stage you can.
This is a classic and must play for anybody. On the Atari 7800, it is a pretty close port from the arcade and ends up being one of the best games on the system.