The laboratory that the scientist of your country has been working, has been captured by the enemy forces and it became the lab of death. The enemy forces have not gone out yet and they should be destroyed before they leave the lab with all of the sources and the information they have. As the professional commander of the country, you should be doing this.
You have four types of guns as in the following Rifle, Gasoline Bombs, Grenades, Tesla Gun. The rifle's bullet can ricochet so you can aim according to that. You can burn wooden blocks with gasoline bombs and you can destroy enemy units that are not in your vision with the hand grenade. Tesla gun can kill multiple enemy units once you shoot it.