This is how you can interact with your friends in the game!
To add friends, you have to open the Play With Friends panel (the happy miner at the top right of the screen). If you are connected to Facebook you will see your Facebook friends that play the game. To add new ones, you just have to tap on the button "Invite", then you will be given options for inviting people.
In the "Play With Friends" panel you will see a maximum of 20 friends (because these 20 give you a 100% income boost). However, you can add an unlimited amount of friends, and always join their Expeditions!
You can find the Expeditions on one of the small islands in the middle of the world map. You need to be connected to the internet and Google Play Games / Game Center for the Expeditions to work correctly.
If you do an Expedition, then you simply choose the one you want and leave your assigned manager to complete it! You collect the rewards at the end of the Expedition. It's as simple as that! Full Page: Expeditions
When you enter the Expeditions menu, you can click on "Select Expedition" to choose from 3 Expeditions. You don't get to see all possible rewards, just one as a teaser! If you like, you can scroll to the bottom and click "Reroll Expeditions" to try and get different/better ones. You can only do this once every 24 hours.
Once you start an Expedition, you will see a timer with the remaining running time. Once this runs out, you can go back to the Expeditions menu to claim your rewards!
Types of Expeditions:
Common Expedition - The most common! You get 2 rewards in total.
Rare Expedition - The second most common. You get 3 rewards in total.
Epic Expedition - These don't appear very often! You get 4 rewards in total.
Legendary Expedition - These are very exclusive and don't appear often at all! You get 5 rewards in total.
Expeditions with friends
If you are connected with friends in the game, then you can help each other out in the Expeditions!
Once you start an Expedition, you will see a friends button on the bottom right. If you click this, you can select any available friends you'd like to invite to help you. If they accept, they will be added to your Expedition and the time left until completion will decrease! At the end of the Expedition, you all get the same rewards.
If a friend invites you to their Expedition and you accept, then you will appear in their Expedition and will help descrease their waiting time. You claim your rewards at the end just like you do for your own Expeditions.