Scavanger Hunt
Both of these 1st 2 ideas are more appropriate for sessions like Cosmic Bingo were you have a younger group of players. We have discussed this in a previous articles. Briefly, the idea is to place QR Codes throughout your hall, have your players locate and collect all of the messages to either win a prize or receive a throwaway for a special game.
Treasure Hunt
Each code hidden around your hall contains a riddle whose solution leads the players to the location of the next riddle. Players need to solve all of the riddles to reach the end of the game and their prize. This can be run as a race or as a game where there are multiple winners.
Both of these games can start, end or include codes on your website. Lot’s of creative possibilities.