The chief architect of Sony's PlayStation game console stepped down Tuesday.

Ken Kutaragi, 56, retired as Sony Computer Entertainment Inc.'s chairman and group chief executive, the gaming unit said Tuesday. The unit is now headed by Kazuo Hirai, SCE's former president and chief operating officer.

Kutaragi had already been relieved of day-to-day responsibilities as president last year but stayed on as chief executive and chairman. In April, he announced his intention to retire from those positions this month.

Though no longer a board member, Kutaragi will hold an advisory post at the gaming unit.

The departure of Kutaragi, an icon among gamers, marks the end of an era at Sony that saw the company dominate the video game industry with its PlayStation consoles.

But it also highlights troubles amid a series of blunders over the rollout of its PlayStation 3 and intense competition from Nintendo.'s Wii console and Microsoft's Xbox 360.

The PlayStation 3 has been marred by embarrassing production shortages and a $600 price tag that some fans said was too steep. It went on sale late last year.