Gamification design using tourist-generated pictures to enhance visitor engagement at intercity tourist sites. - Rapeepan Pitakaso; Surajet Khonjun; Natthapong Nanthasamroeng; Chawis Boonmee; Chutchai Kaewta; Prem Enkvetchakul; Sarayut Gonwirat; Peerawat Chokanat; Ganokgarn Jirasirilerd; Thanatkij Srichok (Ann. Oper. Res., 2025)