Reason
Does not work on MediaWiki 1.27 or above due to the changes in AuthManager introduced in 1.27. It's barely been touched since 2014 except drive by maintenance

ConfirmEdit (CAPTCHA extension) has the same (and maintained) functionality

Also, T204342#4742826 (November 2018)

In T204342#4742826, @Vedmaka wrote:

@MGChecker @Liuxinyu970226 Yup, it was included into ConfirmEdit but it's also good ( at least it was ) to have a simpler captcha-only version. Still, I'd really like it to be upgraded eventually ( especially taking into account that reCaptcha 3 was released already by google ), but unfortunately I don't have enough time for it right now

To-do list

• This task
  • Add maintainers of that extension as subscribers to this task (if they have no apparent Phabricator account, notify them on-wiki or via email if possible and note it here).
  • Add Phabricator project MediaWiki-extensions-reCaptcha as a tag for this task, and remove MediaWiki-extensions-Other as appropriate.
• On-wiki documentation
  • Archive documentation on mediawiki.org (https://www.mediawiki.org/wiki/Extension:ReCaptcha): replace page contents with {{Archived extension|last revision id before archiving|ConfirmEdit|reason=Does not work on MediaWiki 1.27 or above due to the changes in AuthManager introduced in 1.27. Per {{phab|T250641}}.}}.
  • If documentation page was translatable, remove <translate>, visit Special:PageTranslation, and click "remove from translation" (if you don't have the translation administrator right, ask a user who does).
  • Update Wikidata item (https://www.wikidata.org/wiki/Q21678247) associated with documentation page
    • add statement Abandonware (Q281039) to instance of (P31) together with qualifier start time (P580) = the YYYY-MM-DD date that you decided to archive extension (generally per edit history)
    • add qualifier end time (P582) = the YYYY-MM-DD (same date as above) to instance of (P31) = MediaWiki extension (Q6805426)
• Phabricator
  • Mark all Phabricator tasks for the extension either Declined or Invalid. Add a comment pointing to this task when doing so for reference.
  • Archive Phabricator project MediaWiki-extensions-reCaptcha for the extension.
  • Edit Phabricator project MediaWiki-extensions-reCaptcha description for the extension with a link to this ticket.
• Translatewiki.net/translations
  • Remove from translatewiki.net (groups/MediaWiki/mediawiki-extensions.txt).
• Configuration/tests/integrations/etc.
  • Remove tests in integration/config (zuul/layout.yaml).
  • Remove manifest/other references from mediawiki/vagrant if they exist.
  • Remove from https://doc.wikimedia.org/cover-extensions/ if present (requires Continuous-Integration-Infrastructure shell user to delete directly from the server).
• Repositories
  • Empty repository, leaving only the README indicating the repo is archived, and referring to this task by URL.
  • Remove from mediawiki/extensions (along with in .gitmodules).
  • Mark the repository read-only in Gerrit (also edit description to prepend "[ARCHIVED]" and a reference to this task): (provide Gerrit Repository URL).
  • Archive the Diffusion repository for the extension: rEREC extension-reCaptcha
  • Archive the GitHub mirror: https://github.com/wikimedia/mediawiki-extensions-reCaptcha