This scenario shows how Zu Bajie was recruited into the team of pilgrims.
While waiting for the Tang Monk to come (Guanyin was the one who recruited him first and told him to wait until the pilgrim would come), he disguised as a human and lived in a village, where became the son in law to the village squire and planned to marry his daughter. But accidently he blew his own cover and appeared as an anthro boar, causing an uproar. He kidnapped the squires daughter and locked her and himself away in a house nearby. But he didn´t harm her, in fact, he treated her gentlemanlike and cared for her needs.
Sun Wukong found out about his secret and switched places with the woman, appeared in her shape and fooled arround with Bajie, resulting in the boar´s retreat. Wukong battles with him, but Bajie stops the fight, after Wukong revealed who he was and that he was in the company of the Tang Monk. Bajie surrenders and is brought back all tied up to the Tang Monk, where he eventually is welcomed to the party.

I don´t know, why Game Science made Bajie a little adorable fella, while in the novel he is described as big and strong.