The big studio implosion of 2012 was unquestionably Curt Schilling's 38 Studios, former employes of which are the defendant in an ugly lawsuit brought by the state of Rhode Island. 38's failing was so spectacular, however, that you may have missed some of the other studio closings of 2012, which include the houses behind some real pieces of videogame history. From Bomberman creators Hudsonsoft - founded in 1973! - to Sony Liverpool/Psygnosis, which made my beloved Wipeout and Colony Wars series, this year, along with its sagging game sales, saw the loss of some extremely significant developers.
The full list is at IGN.