A free program for Android, by Xlythe.
In Hex, two players connect their two sides of the board by building a path from one side to the other. The game starts with both players placing a single piece of any color on the board. The first player to connect both sides of the board wins.
It's your move
To make your life easier, you can play with your friends on the same device or online on Google+ with the online mode enabling first move swap.
Each player can only move one space at a time, so if you want to move somewhere, you'll have to take care of the current space.