In the beginning, the company worked on the Mana and Seiken Densetsu series, both of which were originally on the Game Boy and Super NES consoles respectively. The company name originates from the legend of a Brownie being a hard working elf, and the elf on the Brownie Brown logo is named Brown. One game that Brownie Brown co-developed that they're famous for is Mother 3, the final installment in the Mother series.
Brownie Brown worked with Level-5 on Professor Layton and the Last Specter, but didn't really help on the game, itself. Instead, they worked on the new bonus mode in the game, London Life. This bonus RPG, unlocked after the completion of the game, is said to add another 100+ hours to the game.