A recent ruling from US District Court judge that an iPhone Tetris clone is infringing on the Tetris Company's copyright has potentially positive ramifications for other victims of cloning.
But the issue isn't as straightforward as it might immediately appear...
I don't have the answer to this, by the way, but I do think it's interesting. The reason I'm asking is that, as I write, Puzzlejuice, Asher Vollmer's brilliant blend of Tetris, Bejeweled and Boggle, is right behind Pajitnov's hardy perrenial in the iPad app charts. It's been out a little less than a week and has had no marketing by the developer.
Over at its IGF listing, designer Asher Vollmer describes Puzzlejuice as, "a game that will punch your brain in the face." That doesn't sound very nice, Asher. Luckily, Puzzlejuice looks a lot more pleasant than that.