DeNA fought against GREE at a trial about intellectual property until today. And DeNA won.
In September, 2009, GREE charged DeNA in an intellectual property theft. GREE ran fishing social game for mobile "Tsuri ★ Sta(釣り★スタ)" from May, 2007 , and DeNA ran fishing social game for mobile "Tsuri ge town2(釣りゲータウン2)" from February, 2009. GREE said that it was copied the design of the scene that caught a fish by DeNA and charged them. Actually, they were similar.
This created a great debate in Japan. In the first place what is the copy? What is the difference between universal design and copy?
In February, 2012, the Tokyo District Court accepted a suit of GREE in first trial judgment and ordered DeNA to shut down a Tsuri ge town2 and pay 234,600,000 yen for GREE . Of course, DeNA appealed on the same day.
In August, 2012, the intellect fortune High Court canceled first trial judgment and dismissed request of GREE. the presiding judge judged that the design of Tsuri ge town2 was "common expression", and this did not correspond to an intellectual property theft. Naturally GREE appealed on the same day, too.
However, the Supreme Court gave decision to reject a final appeal of GREE today. A lost case of GREE was settled in this.
By the way, there is the problem that is more important than a trial in GREE and DeNA. Because their growth slows down. LINE's Game apps, Puzzle & Dragons, Nameko Saibai Kit series, Dark Summoner, etc... Many rivals appear now. In the first place, "Tsuri ★ Sta" and "Tsuri ge town2" are popular games in a futurephone. In other words they are the old-gen social games. Next-gen social games appear in sequence now. It is useless to use time and a resource for a trial this situation.