Multiple Device Gameplay App

Hey guys,

I'm trying to design a game (that is played in person) in which you connect multiple devices together via the app. So for example, if everyone had the app open, and one person clicked a button, it would have an output on everyone else's phones. Is this possible, and if so, how?

Read about MQTT.

Yes. Use Firebase or CloudDB realtime databases or possibly a Google Sheet.

The following are not games, but the examples use principles that can be used in a game.

Here is an app that uses a CloudDB to monitor your family herd How to: A Family Chat app built with the MIT CloudDB component

I have made a chase app and a maze game that are multi-player. You probably can do something similar.
Here is a two person game Mountain Kingdom - a chat real time two player, two device game using the CloudDB and a Canvas . It can be adapted for more players.

Here is a Firebase based game by Hossein chat | Search Results | Hossein Amerkashi's Blog

Merry Christmas, Wesołych Świąt, Feliz Navidad, God Jul, Joyeux Noel, Καλά Χριστούγεννα, Happy Christmas, Veseloho Rizdva, Prettige Kerstdagen, Frohe Weihnachten!, 성탄 축하 , Buon Natale, 聖誕快樂 , 圣诞快乐, Sretan Božić, C рождеством!, عيد ميلاد مجيد

do u mean multiplayer games like PUBG or so?