1984, Jet Set Willy was released. A great game that every kid at school wanted. Of course we all wanted a copy, but it cost £8 here in the UK, which was several weeks' pocket money.
Copying games then involved finding a kid whose Dad was seriously into Hifi and had a stackable stereo system, then we'd copy it with their tape to tape system. But JSW had this as the cassette inlay.
How this works? When the game loaded after about 10-15 minutes, it would ask what colours were in Grid square A5, or H9 etc. Get it wrong twice and the game would exit and you'd need to start over.
(If you're wondering what happens if you're colour blind - you could write to the publishers and if they accepted your complaint, they would ask you to send them the game and would give you a cheque to cover the refund)
Of course, kids are determined and inventive, and this was well before photocopiers or digital cameras, so we would spend our lunchtimes with pencil and paper writing down every single combination...
It was a good game, with some great music, but really really hard.
(Credit to https://intarch.ac.uk/journal/issue45/2/1.html for the picture, and the page also goes into more depth)
More like "before easily available color photocopiers". Most copiers could only do black and white copies, which this scheme was probably specifically designed to make useless.
The inks used couldn't be faithfully scanned/replicated. So even color copiers were useless.
My father had a friend from his childhood who ended up owning a graphic design studio, and sometimes he would have to have these replicated using classic photography.
When I think back, we jumped through a lot of hoops to get a free game when we could have just spent a couple dollars lol