This letter is real, not some photoshopped wish. It was uploaded by redditor Fryd_ after he found it while playing with his niece and nephew. He told BuzzFeed:
I came across the pamphlet whilst playing Lego with my niece & nephew at their Grandma’s house and it struck me as particularly modern message for something written 40 years ago. I thought the toy-makers of today could learn a thing or two!
It’s a beautiful message and rings just as true today as the day that it was tucked inside a brand new box of Lego over 40 years ago.