10. Collectables
Fetch quests are an expansion method worthy of an article rant of their own, but some of the generic coin systems continue to stump my reasoning abilities. As with everything, the environment should define the sorts of things you can find, like Bottle Caps in Fallout. Aside from money and swapables essential to progressing in the game some of the things you can find in a game are just ...weird. Skyrim has an amazing assortment of books which actually added depth to the world. Things that actually build on the game are fine, but shrunken heads and red spades are among some of the odd things I've been rewarded for finding. It's all very well to have the player find things that make sense, but to have to journey around the game world to collect things that are of no use in terms of advance such as trinkets rather than practical weaponry, shields armour and so on. Keep the game world relevant to the game experience. That should be rule one in the handbook. Shame most new games aren't supplied with a handbook any more.