Check out these help docs in our manual. They cover tags, and how to use them in a few ways.
https://hyperpad.zendesk.com/hc/en-us/articles/202466275-Object-Tags
https://hyperpad.zendesk.com/hc/en-us/articles/202467545-Applying-Behaviors-to-Tagged-Objects
https://hyperpad.zendesk.com/hc/en-us/articles/115001430843-Collided
https://hyperpad.zendesk.com/hc/en-us/articles/205763199-Part-6-Adding-enemies