GameSpot writes: "Last week the NPD Group, the industry standard of game-industry research firms, released its US sales figures for 2008. However, the company's top 10 game rankings only tracked individual products, or SKU (Stock Keeping Units), sold at retailers in the US.
As a result, it was unclear how two of the year's biggest rivals--Guitar Hero World Tour and Rock Band 2--fared against one another. Besides being multiplatform releases, the two solidly reviewed rhythm games each came in various retail configurations, such as a la carte or with one or more instruments."
