When working in a textiles warehouse I would make it fun by imagining someone I’d met walking down a familiar street while showing off the shirt/hat/etc. I just sorted/tagged/profiled in a ridiculous fashion show montage, then turning to me with a smile and a wink or thumbs-up and saying, “Thanks, man!” or similar after I finished X items depending on the day’s quota. The person would then step into a crowd behind me cheering me on, who I would imagine turning around and “hi-five”-ing one at a time after arbitrary milestones to celebrate my progress.
To come up with this idea I asked myself who would be disappointed if no one in the world were willing to do any job resembling mine anymore and what would they be losing, then optimized the generated examples for salience and awesomeness.
The game aspect is trying to get a higher “score” of hi-fives at the end of each day. Sort of like Tetris or Bejeweled where you always run out of space/time eventually, but can play again to improve your score.