Joining a Hero Hunters Alliance will help you get the most out of the game. Joining an alliance while your logged into your Google account will unlock a large achievement. It can be tricky to find one to join at first as many of them might have a high team level required to join. The max number of people to join is 25 and this limits doesn’t seem to get any bigger.
Inside the Alliance menu you are able to do a few different things from communicating with other members to blocking people if you are having problems with them. There doesn’t seem to be any real purpose of joining an alliance except to talk with other players and create a team. If you wish to leave you can do so at any time.
One thing you can do if your having a hard time finding one or you would like to start a new is to create your own alliance.
If your looking for more related information check out the Hero Hunters Wiki.