Time/Money is a poor metric for reasons many have posted. I think my formula is pretty decent. It is a pretty good approximation of my actual feelings about a game. Let f(t) be the function of fun over the course of a game. Let E be the constant that represents my average entertainment during my freetime (when I could choose to play a video game or not). Then the value of a game to me is the (integral on t of (f() - E)) / (cost of the game + small constant) + various bonus constants. These various constants tip the scales a bit but don't generally massively change the overall value. They include positive bonuses for: * Open Source * Cross Platform * "Independently" developed Games that have done very well by this metric: * Civilization I, II, IV, Alpha Centauri, the original Colonization * Half Life (original) + free Counterstrike and Day of Defeat mods * Dwarf Fortress (bay12games.com) * Company of Heroes * Starcraft and Warcraft II