TL;DR It's really curious why they would change this date, and specifically to a date that coincided with the Saturday after E3 in 2009. I suspect we'll never know the real reasons, or the real...
TL;DR
At E3 in 2009 Tetris Company and their external PR people backdated the year of creation of Tetris from 1985 to 1984, specifically 6th June 1984, and then held a 25th Anniversary party for it on 6th June 2009. All previously existing printed material, copyright filings, documentaries, interviews with Alexey and Hank from before June 2009 state the game was created over a period of three weeks in 1985.
It's really curious why they would change this date, and specifically to a date that coincided with the Saturday after E3 in 2009. I suspect we'll never know the real reasons, or the real history of a game whose origins are still shrouded by the iron curtain. Hank and Alexey's story has changed frequently over the years, this 1985/4 date change is just the most recent and most perplexing.
The 1993 interview cited at the above link says it was created in "three weeks", which means if it was first playable in June 1985 it certainly seems that it must have been created just before then.
Given that this happened 15 years ago, the "new" date is now embedded in the public record and Tetris Company are sticking with it. The "old" date had existed for 20 years from 1989 to 2009. Thankfully we have printed material, scans on Internet Archive, Wayback Machine, and Wikipedia's own edit history function we have more than enough information to call upon to see through strange historical revisions like this.
TL;DR
It's really curious why they would change this date, and specifically to a date that coincided with the Saturday after E3 in 2009. I suspect we'll never know the real reasons, or the real history of a game whose origins are still shrouded by the iron curtain. Hank and Alexey's story has changed frequently over the years, this 1985/4 date change is just the most recent and most perplexing.
The 1993 interview cited at the above link says it was created in "three weeks", which means if it was first playable in June 1985 it certainly seems that it must have been created just before then.
Given that this happened 15 years ago, the "new" date is now embedded in the public record and Tetris Company are sticking with it. The "old" date had existed for 20 years from 1989 to 2009. Thankfully we have printed material, scans on Internet Archive, Wayback Machine, and Wikipedia's own edit history function we have more than enough information to call upon to see through strange historical revisions like this.
How convenient that both anniversaries are exactly 5 years apart. It looks nice and makes for some pretty advertising material every 5 years.