Game Economics: The role of money in single player games, Intro

You've heard them under all different names: Gold. Zeny. Galders. GPs. Bronze. Silvers. Platinum.

Let's talk about the most basic reward you can give a player: MONEY.

Part 1: What is the role of money in a single player game for the player?

1. It provides a resource to replenish consumable resources.
2. It provides a resource to upgrade his character's power.
3. It provides a way to affect the game environment.
4. It can serve as part of the reward mechanism. 

Part 2: It is impossible to look at money without looking at it's logical inverse: prices in a single player game. What are the roles of prices in a single player game for the designer?

1. It provides a way for the designer to set player power growth by limiting availability of items.
2. Prices can be a subtle hint as to what "Power Range" the player should buy.
3. Controlled/Constant reward mechanism for doing certain actions.

Part 3: Then what are the common pitfalls of not balancing money correctly?

1. Making money do nothing - The "I am a millionaire, but no one sells anything useful."
2. Excess of money trivializing money - The "I have enough money to do whatever I want. No limits!"
3. Paucity/Unevenness of reward - The "Why do I bother doing quests for 3 pennies when I can kill a sheep for 12,000?"
   
4. Making money overpower the player - The "I just bought my level 99 weapon at level 3 and now the game is EZ-mode." 

Part 4: Solutions and various money controlling mechanisms.

1. Hyperscaling - Making whatever money the player has obselete by scaling the prices.
   
2. Money Sinks - Making available convienient ways to get rid of cash like gambling.
   
3. Nickel and Dimes - By making boring processes of acquiring money have penalties to acquisition.
4. Supply Control - By slowly expanding the shop selection.