Retention marketing, in the context of out-of-home entertainment, is getting people who have already been your guests to (a) visit you more frequently and (b) spend more money with you. It includes several disciplines:

• CRM (email, SMS, and app messaging…even sum forms of targeted advertising)
• Guest services/relations
• Loyalty programs, loyalty marketing
• Season Pass, Subscription, Membership programs

Some might say it also includes the experience guests have at your venue.