You have have to fight alone against a branch of enemies who will be targeting your base and trying to attack you. They will come towards you and as the game advances, their number will increase. Moreover, they will come with a greater speed in higher levels. So, this would be a very hard challenge for you to survive. But nevertheless, you will have high category weapons to kill them. You will be provided with different type of guns with high accuracy and damaging capability. By getting more kills, you can collect new powerups and weapons along the way. There are three modes in this game- defense, survival and experiment mode. The survival mode is the hardest mode. But here you will be provided with much point to buy better weapons. You can choose the best weapons for you from the categories like pistols, magnum, auto-shotguns, light machineguns, assault rifles etc. This will help you to get going against the enemies.