Roblox, the gaming company that went public earlier this year, has lessons for other internet outfits aiming to attract younger users even as its own audience gets older.

Developers Michael Cooke, left, and Navin Lal, right, work on their website at Roblox in San Mateo , Calif., on Thursday, March 31 , 2011. Roblox is one of the top ranked kids' gaming sites on the ...