My son has been playing Costume Quest for the last couple of days and makes a point of showing me how full his candy bag is getting every couple of hours.  As I watch him play, he's taking the time to hit every object in the world that can drop candy and makes sure to pick up every piece on the ground.

Today, he called me in to read one of the conversations to him.  There was a Stamp vendor that had upgrades he could buy in exchange for candy.  After reading them all to him and explaining that he can use candy to buy them, he says "No...I don't want to."  When I asked why he said "I don't want my candy to go down".

This got me thinking about how we convey the importance of things to our players.  I've spent my whole life playing games and have learned that buying upgrades is almost always worth the cost.  Besides, in most games you quickly earn the spent money back anyway.  But, my son doesn't have this knowledge from his perspective the most important part of this game is the accumulating of the candy.

While I'm not suggesting that we design every game for kids to be able to understand it, I do think it's very important that we show what the value of things are.  A description what something does in game is not always enough to give the player a true understanding of how it can change the game for the better or simply be worth the cost we have associated to it.  I've been in dozens of game design discussions where someone will say "Like Halo Reach did it" with the assumption that everyone had:

1. Played the game being referred to
2. Remembered exactly the part of the game
3. Actually fully understood the mechanic or situation being described