The series became more popular and better known during the Pluto era, when entries number 3 and 4 were released. These games were more open-ended, featured improved graphics and gameplay, and were generally better received by the public. They were released in 2009 and 2010 in Japan, with Western releases coming only after both games were out already in Japan. Dead Souls, a zombie-themed spinoff, was released in 2011.