[niggler]

Are you supposed to "click-drag" or "click the piece then the cell"? How about on iOS ?

My point is that, while the one-liner captures the idea of the captcha, the summary doesn't explain how to actually execute.

[mich41]

So add a short explanation at the end.

Starting with "Hey, let's solve a CAPTCHA because I'm not sure if you are a human" and burying information which side the user is supposed to play somewhere in the middle of the text would make it a major PITA.