LOS ANGELES - IT WAS spring in what was then the Soviet Union when a mathematician in Moscow with a penchant for puzzles created a 'Tetris' computer game still going strong 25 years later.

He was inspired by a classic puzzle consisting of a box made of five plastic pieces that could be assembled in myriad ways. The challenge was to reassemble the box.

Alexey Pajitnov made a computer program that he came to call Tetris, which basically involves a player manipulating variously shaped blocks dropping along a screen with the goal of getting them to mesh into rows without gaps.

Blue Planet Software chief executive Henk Rogers was at a major Consumer Electronics Show in 1988 when he spied Tetris. He was scouring the event for videogames for the Japan market.

Mr Rogers arranged to publish versions of Tetris for computer games. Early in 1989, he and Minoru Arakawa of Nintendo of America went to Moscow to license the rights to the videogame.

Nintendo saw Tetris as an ideal fit for its Game Boy handheld devices. Since Mr Pajitnov's game was considered Russian property, licensing was negotiated with government officials.

Mr Rogers and Mr Pajitnov kicked off a Tetris 25th anniversary celebration on Tuesday at the opening of a premier E3 videogame industry gathering in Los Angeles.

Mr Pajitnov now divides his time between homes in Moscow and Seattle. He and Mr Rogers, through Blue Planet, license Tetris rights to game makers such as Nintendo and Electronic Arts (EA).

More than a million Tetris games are reportedly played daily at a tetrisfriends.com website launched in March.

'I never supposed it would be this big' Mr Pajitnov said. 'I was the best Tetris player in the world at one point. Now, I'm a good player but not a great player.' -- AFP