Firstly you have to create a hotspot on your phone. To do this, go to Settings > Mobile Hotsport and tethering > Mobile Hotspot. Tap on it and then enable the service. Configure the name and the security. Since you're playing locally, use it without password, therefore choose Open.
Once you configure all the things, the wireless network should be visible to your friends to connect to. If you need Internet connection, activate the Data Connection as well. Switch to 4G to have better speed.
Keep notice that it will drastically consume the battery.