Manuals (as in Instruction Booklets, not the Opposite to Automatic)
I've got this fond memory of being in the back of my parent's car, driving back from the electronics store, a game box on my knees and an instruction booklet in hand. I used to get car sick like crazy, so reading in the car was a big no-no for me, but this didn't stop me from trying to savour the game before I could put the cartridge in the console.
To read the plot, get to know the characters, look at all the pictures, imagine how the game played judging from the written tutorials... 15, 20 minutes of forced waiting became a ritual I was so fond of that gradually disappeared as physical releases abandoned bundled manuals1. Even when I got my games myself and there was no car ride to get sick in, the very first thing I did after buying them was opening up the box and read the booklet. Curiously, I've never done it with digital manuals2...
I think it's a big shame they're mostly a thing of the past now, and I'd love to have at least a digital version of a manual for my next game. Much love to indie games that do this!