You are part of a army corps and your men are instructed to leave your position, but it seems that the enemies aren't going to leave you alone. you need to defend yourself till you are able to escape the combat zone. You would need to shoot the enemies that appear on the screen. Each kill would earn you money and you can use it to buy some upgrades or even men to fight for you. The game would be harder as you make some progress, but with the help of a few upgrades, you can get through it.