Alright, good sir. Expect to hear from me in a few days with progress.
Could you PM me with your site and an example of a page that you'd like to be unlocked via a captcha?
It wouldn't be the whole page, just the part that goes between the hide shortcodes that would be hidden.
Just like that plugin(like-gate) does. A download link for example.
I'll PM you a page and tell you which part I would like to hide from that page.
You can make the captcha appear(instead of the hidden content) on the page as soon as it opens, or make the captcha appear when they click a link/button.