The dynamics of the program should be like that of GTA (Grand Theft Auto), movement of the character, interaction options with objects, and other players/NPCs. 
The map/arena setup will like an exhibition hall with reception, booths/stall, banners. 
Two different signup options: first visitor, second exhibitor. 
It will have a visitor sign up like an MMORPG, with character customizations (take a picture and the character looks like you feature). The visitor can move around freely in the hall, interact with different objects like posters, vases, elevators, escalators, objects/products in kiosks/booths.
Exhibitor will have a sign up with design your stall/booth feature, with detailed entry needed regarding their products, adding 360 degree pictures/videos of their products, details and description (these products are interactable by visitors). Banner/pictures display on booths. Video call and setup appointment feature for the booth so visitors can directly connect with the exhibitor if one is online at the time or setup an appointment for available predefined slots.