I've been thinking about this in relation to the video game community and there doesn't seem to be as much anxiety around considering puzzles as games. There are countless video games that are just a series of single-solution puzzles with varying degrees of narrative framework around them.
Comments
If I'm completing a CAPTCHA that asks me to put a puzzle piece in a correct spot, that's a task, not a game.
If I'm playing a Disney adventure and now I'm Mickey Mouse putting a puzzle piece in a correct spot, now it's absolutely a game.
Driving to work and CAPTCHA aren't games because they operate towards real-life goals, and not to a play space.