OK, so unique visitors are very important. Going beyond the concern for sustaining unique visitor growth on a limited marketing budget, why did you list the tracking of marketing costs per unique visitor as a key metric?

Marketing budgets are certainly limited, and cost per unique visitor is a quick way to figure out how many unique visitors an operator should be able to drive to the site with next month's marketing budget, but the key insight gained from trending this metric is the efficiency of the marketing campaign relative to other games with a similar business model, play mechanics, and genre.

It is important to understand that the ability to obtain users from online ads has a finite limit -- the number of gamers who view ads in a given time period.

In particular, when you think about pay per click rates (PPC) of ad campaigns, there is a fairly limited number of potential online game customers and there are a lot of online game operators trying to buy ad inventory for those customers to click through to get to the operator's game.

As the online game market continues to expand and larger operators with bigger ad budgets enter the fray, we expect to see the PPC and Cost per Thousand ad views (CPM) start to creep upward. So the operator that has the lowest marketing cost per unique visitor is likely the most efficient at buying the limited online ad inventory and in the process driving up the cost of ads to their competitors if not locking them out of critical ad inventory altogether.

Lots of unique visitors is no doubt a good thing. Getting visitors to engage with the site's content is even better. You mentioned several metrics concerning registered users. What is the best way to leverage them to gain a better understanding of how well a game is being operated?

Registered users of a game, even users who have never played the game or have not played for months, represent the current customers of the game. This is the group of people who are the best to market new releases of the game, products related to the game, and most importantly the next game you want them to try.

People tend to skip past the total registered users of a game to get to current active players and paying user counts. However, there is still some important information that a close look at registered users will reveal.

In particular, a breakout of the number of new registered users each month trended over time will be a strong indicator of if the game is peaking.

Tracking the percentage of unique visitors that convert to new registered users of the game each month and comparing it previous months can provide insight into the effectiveness of various marketing campaigns.

In addition, tracking the average marketing cost per registered user on a monthly basis in addition to understanding how well the marketing budget is performing, can also indicate how well word of mouth and other free sources are driving users to the game -- if registered users are stable or increasing when marketing costs are stable or decreasing, it is good indicator word of mouth is starting to drive users to the game.