Do it that way (just idea how to solve that):
create a Usergroup "Registered, can play" and create a Cronjob in your vBulletin which does:
at 7.00am it moves all Users from "Registered" to "Registered, can play"
at 6.00pm it moves all Users from "Registered, can play" to "Registered".
Set the Arcade-Group-Permission like that:
Registered -> can view but not play
Registered, can play -> can view and play
That would be a solution