For centuries, alchemists have tried to discover the formula for turning lead into gold. In more recent times, programmers have tried to discover the "formula" for making a good game. So what exactly makes some games enduring classics, while others aren't even worth the cost of printing the instruction booklet?

Graphics and sound? No, the original Zork and Infocom all-text adventures didn't have any, yet they were great. Difficulty? A tough game doesn't automatically equal a good one. A good arcade-to-home translation? Then why doesn't everyone like Space Panic for the ColecoVision?

A game that has staying power? But what makes such a game?