Email hello@mapcade.com. Tell us what happened, what you expected instead, and which iPhone and iOS version you are on. If a round scored something that looked wrong, say which game and which country.
Everyone needs to be on the internet, and everyone needs the app: a room code does nothing in a browser. Codes are four to six letters with no vowels, so there is nothing to mistype into a real word. If the code has stopped working, the room has probably closed itself, which happens two hours after the last person leaves. Make a new one.
Mapcade asks for the camera the first time you scan. If you said no, iOS remembers it: Settings, Privacy and Security, Camera, Mapcade. You never have to scan. Every room code can be typed in by hand on the join screen.
Check the speaker button on the title screen, then check the silent switch on the side of the phone.
Your name, your best scores and which games you have seen lately are kept on your phone and nowhere else. Deleting the app deletes all of it.