Register Validation Step

This module will allow you to set a step before register. work on this path user/register/validation
So, you can alter this step and add your fields and validate visitor data before sending him to user/register page.
The visitor can not open user/register directly before pass the validation page.

This module will create new empty form called "register_validation_step_form" showing before regular user register form. So, this mean you should implement hooks to alter validation and submit processes of this form to do your needful validation step process.

This module useful when you want to validate this user data before sending him to register form.
We use it to validate this user he is a real citizen then getting the full benefit of Drupal user register form.