ok, i guess. a bit low compared to COD's 30 million
i hate to think of id as a "niche" developer.
You can't compare RAGE to a game that has higher advertisements costs than RAGE had as total costs. Furthermore, COD is an established brand with yearly updates and with its cliché setting as a modern shooter in a realistic setting, it appeals to the masses.
RAGE might be compared to Borderlands in sales, which was also the game of a new franchise with a semi-known (on the basis of console games) developer and it also has a similar setting although it had a different focus (more coop, more character development, less unique settings, etc). After four weeks Borderlands had slightly lower but steady sales probably due to the good critics the game got. Compared to Doom 3, RAGE sales are pretty horrible although with the former, you only had one platform (at the start).