In a statement to the press, EA (EA) said it was naming Larry Probst as executive chairman while it searches for a new leader. Probst was the Redwood City, Calif.-based firm’s CEO from 1991 to 2007, when Riccitiello took over. Probst has served as EA’s chairman since 1994.

EA also said its revenues and earnings per share will be at the low end or below its January guidance. The company reported lower revenues for the last three months of 2012 than it did for the same period a year earlier. EA had the top-selling video game in February with its action-horror title Dead Space 3. But U.S. retail sales of new video games fell for the fifteenth straight month, year over year. Sales of new video game hardware, software, and accessories fell 25% from a year earlier to $810 million in February, the NPD Group reported.

The publisher’s stock is trading at $18.71, down from $61.40 in 2007 when Riccitiello took over as CEO. EA will announce results for fiscal 2013 on May 7.

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Videogame makers and publishers are entering a period of uncertainty as technology alters the way consumers play. Increasingly, gadgets made by the likes of Apple (AAPL) and Google (GOOG) are eating into the profits of traditional console manufacturers like Nintendo (NTDOY) and Sony (SNE). Game publishers EA and rival Activision Blizzard (ATVI), in turn, have had mixed results trying to adapt. In addition, digital sales have begun threatening the once-steady retail business.

“We thank John for his contributions to EA,” said Probst in a prepared statement. “John has worked hard to lead the company through challenging transitions in our industry and was instrumental in driving our very significant growth in digital revenues.” The decision was described as mutual.

In a memo sent by Riccitiello to Probst, the outgoing chief highlighted the company’s growing digital business. At his direction, EA created an online games platform dubbed Origin to distribute titles over the Internet. The company, which controls lucrative franchises such as The Sims, Madden NFL, FIFA Soccer, and Need for Speed, has tried to find ways to make more of the considerable intellectual property it owns. Riccitiello also oversaw the acquisition of PopCap, a mobile games maker that created the popular Bejeweled.

But EA’s transition to a more digitally oriented business hasn’t gone smoothly. Earlier today, it announced that it had sold more than 1.1 million copies of its city-building PC game SimCity in the first two weeks it was available. About 54% of those sales were digital versions, downloaded via Origin.

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But the launch was widely derided in the games press for severe technical difficulties. For days, players had trouble downloading the game because demand overwhelmed EA’s servers. The technical issues, which have not yet been entirely resolved, caused some reviewers to revisit their initial assessment, lowering high scores that can drive sales. EA announced it would give registered users a free title to make up for the problems.

In 2007, Riccitiello’s incoming mandate was to find ways to pare down the sometimes massive costs associated with developing mainstream titles. Budgets for high-profile games like EA’s Battlefield 3 can easily spiral into the hundreds of millions of dollars. He also vowed to find new revenue streams in comics, television, films, and toys.

Despite a few successes, Riccitiello had yet to score an outsized hit. Activision’s Skylanders franchise, which appeals to younger children, generated more than $600 million in the U.S. alone since its October 2011 launch, according to NPD. Activision previously announced that the franchise had surpassed $1 billion in global sales. In 2012, the combined sales of Skylanders Giants and Skylanders Spyro’s Adventure toys outsold the top action figure lines in the U.S. and Europe, including Beyblades, Star Wars, and Transformers, according to the company’s internal estimates.