In the classic version of check in, there were attributes that you could configure from the Check-In Type Detail block for Success Template Display Mode and Success Template, which allowed churches to use lava to define what is shown at the end of a check in. 

This feature enabled recipes such as this one - https://community.rockrms.com/recipes/385/event-specific-custom-check-in-success-messages - allowing churches to see at a glance which requirements a person has completed when they check in. For example, after checking a camper in for high school camp, you can see at a glance if they have paid their balance, have a signed waiver, and are placed in various groups such as the bus group, small group, team, etc.  Included in this idea is a screenshot of the earlier iteration of this from the recipe, as well as a more recent version where we utilized font awesome icons and set the Success Template Display Mode to replace the message the check in normally shows.  

We've also used this with mobile check in to show fun "you're all set" gifs for college ministry. 

As reported in this Github issue - https://github.com/SparkDevNetwork/Rock/issues/6140 - the functionality no longer exists in NextGen check in. 

We would be very appreciative if the functionality could be restored so that NextGen has feature parity on this issue with classic check in. We would also be open to discussing enhancements to make the functionality shown in the recipe above simpler to achieve for other churches without the degree of setup that is currently required. 

An enhancement to this idea would be to allow the prevention of check in from happening at all if certain conditions aren't met (the conditions that show red icons in the screenshot). Currently if we're doing a camp check in and rock prints a wristband but shows a red icon, we send the camper to a registration solutions table and throw away the wristband. The wristband is then reprinted on a successful check in.