I find that the Rubix Cube is the best way to kill time. The way of playing it, makes the human mind think, thus it doesn’t really count as wasting time perhaps.

How to play:

Users will have to mix the square faces on the cube around first, or have a friend do it for you. You have solved the game when all faces of the same colour forms a entire face of the cube.

Perhaps, they can have the rubix cube on a digital platform. In it, as an application, users are able to reshuffle the square faces if they are stuck at it for too long. I think that this encourages the user more, as they are given a new opportunity.