Use UP and DOWN or W and S to choose a position, use LEFT and RIGHT or A and D to choose a unit type, press SPACE to send the unit.
The aim of the game is very simple: get your men to the other side of the map without letting the enemies men get to yours.
Every time one of your men gets to the other side, the territory bar (at the top) will move to the right, and when an enemy gets to your side, the bar will move left. If it goes all the way to the right, you will win or if you are ahead when the time runs out, you will win as well.