In real life, people make decisions every day on what to buy, and we base those decisions on how we feel our purchases will enhance our lives. We buy this detergent because it’ll clean dishes more efficiently and that overstuffed chair because it’ll look so great in the living room and it’s comfortable to read in. We buy ridiculously huge stuffed animals because their comical appearance makes us happy with laughter, and we buy $7,000 electronic gadgets and $400,000 cars to make a statement about our wealth and status.

The infamous, short-lived "I Am Rich" iPhone app did nothing other than cost $1000, leading six people to willingly buy it for the exclusivity and status.
Inside of a game, that mentality doesn’t change. Whether we’re purchasing real, tangible objects or virtual, pixellated images, the driving question behind whether or not we pull out our wallet is the same– what will this do for me?
The general purpose of virtual goods (VG) is to make game play more interesting, more engaging, more enjoyable– and also to make game developers more revenue. In the case of casual social game developers (particularly those on Myspace and Facebook), VG are their only driving components for revenue, with the following understandings:
- Typically, users exchange real money for the game’s virtual currency, then use that currency to purchase VG– however, the VG are the end goal, so by the transitive property, users are paying for VG
- For the sake of simplicity, VG refers to both objects that can be obtained and actions that can be performed within the game
But even for games that have an initial upfront cost (like the Sims) or that require a paid subscription (like WoW), VG can still be a solid source of revenue. Either way, if developers want to make any profit from VG sales, they need to really understand the dynamics of their game and tailor their VG appropriately: users will not want to pay for virtual goods that do nothing to enhance their game play experience.
How can VG enhance game play?
- Progression: owning the item allows users to increase skill points, which assists in leveling up (e.g. better weapons that enable more wins)
- Amusement: owning the item makes the user happy (e.g. unique-print wallpapers or personality-reflecting furniture for a user’s virtual room)
- Status: owning the item allows the user to show off either wealth or devotion to game play, or both (e.g. highly expensive or limited-supply objects)

Examples of virtual goods in Extreme Basketball that enhance game play by increasing the user's odds of winning matches.
And for VG as actions, enhancement comes predominately via progression and amusement.
So if you’re a game developer, when deciding what sort of VG you’re going to make available to your users, ask yourself: why would my users want this? How does this add worth to my game for them, and how does it make their experience more enjoyable? Once you make VG valuable and make that value evident to your users, the purchases will happen and your percentage of paying users will grow.
Once you go down the path of selling virtual goods you have to be real careful about the accounting of these goods in the rest of the game.
Like some games let you delete items without confirmation, items go missing after the game is reset, or while your room is rearranged and you lose the internet connection, etc.
This is real money lost to the players and they would be pissed off.