Goal of the game is to have more armies than your opponent. Every turn you (or your opponent) receive an army with a random strength between 1 and 20.
The next army that is about to be placed is shown on the center bottom of the screen, next to the infos about your stats.
If you place your army next to one of your other armies, it strengthen them by 1, max strength is 20. If you place it next to enemy armies, it takes control of them if the strength is higher, otherwise nothing happens. The strength of each of your armies adds up to your total, and if it is higher than the total strength of your opponents army, you win!