Also worth noting: Mumbo Jumbo, the game maker responsible for such superhits as Slingo and and Jewel Quest, has an assortment of games packaged together -- and that collection hit number six last month, beating out big-name games like Spore from EA (#11), Grand Theft Auto IV (#12) and Batman: Arkham Asylum (#16). NPD's David Riley says it's "not unusual" for casual games to beat out bigger games since their prices are considerably lower than a more traditional video game.
Other casual games that are rocking the top 20 include: Nancy Drew: Ransom of Seven Ships from HerInteractive (#18), Real Deal Slots and Reel Deal Slots Adventure from Phantom EFX.
While having casual games beat out more traditional video games in the PC space isn't necessarily new information, but it's certainly a testament to how the average consumer is drawn to pick-up-and-play games like Zuma (and games not listed on the NPD chart, such as Cafe World and Mafia Wars on Facebook, et al.).