Vanillicon for WordPress
This is a WordPress plugin that lets you set Vanillicon v1 as the default avatar. Vanillicon is an identicon generator by Vanilla Forums.
This does not interfere with Gravatar. If a user has a image set via Gravatar, their Gravatar image will be shown instead.
Tested with WordPress v5.3.
vanillicon.php in your
/wp-content/plugins directory and activate the plugin from the admin page.
The hash parameters used for Vanillicon v1 match the Gravatar plugin's for Vanilla.
Vanillicon v2 can't be used because it outputs an svg image, which Gravatar doesn't support for the default avatar fallback.