Not including RPGs since they are always have been and will be (for the most part) long games. But especially 2D games I always found to be rather short games on average, maybe averaging out around 6 hours? Definitely short enough to clear on my first day of playing. Arcade games are usually only 1-2 hours max. DLC has gone too far in many instances but older gamers, especially carts, were quite expensive. I think I sort of get your point but I don't think your analogy was too great.