From the announcement:
On The Lamb Games & Mongoose Publishing are teaming up to bring you a roleplaying game set in the Brushfire world. Historia Rodentia will be the first Brushfire supplement for their upcoming 'Legends' Roleplaying system based on the much loved RuneQuest II system, and will cover the areas and peoples of Aquitar, Civitas, Scyzantine, and The Vandalands. Future supplements will cover additional areas.Link: On the lamb Games & Mongoose Publishing
Historia Rodentia Roleplaying is expected to be released May 2012, price is TBD.