What are Ferdinand and Miranda doing when we first see them in Act V? What does Alonso immediately resign when he sees prospero?

When we first see Miranda and Ferdinand in Act V, they are playing chess together.

Alonso immediately resigns when he sees Prospero because he knows he is guilty of wronging Prospero. He knows his actions have brought Prospero's revenge upon them all. He resigns and begs Prospero's forgiveness.