The problem with MMOs is that many of them don't even sell on retail or even at digital distribution - they go straight to their business model(subscription, F2P, etc...) . One way I think to include MMOs and other subscription-based games in the best-sellers list is to make this rule:
- Subscription-based games' sales will be be counted from it's total lifetime subscriptions.
- If the total lifetime subscriptions aren't available, the games' sales will be counted from total retail boxed sales.
- If both above aren't available, count the games' sales from max known value of it's subscriptions.
Makes prefect sense, doesn't it?
By the way, Lineage 2 has sold over 14 millions copies on PC (or atleast 14 millions subscribers lifetime): http://www.plaync.com/us/games/l2/buy.html
