In one sentence, describe what the following article is about:

Dead Trigger 2 is a first-person shooting game, so when you move your cursor, it will turn your head into the direction of your mouse.  Moving your cursor forward will make your character look up. Moving your mouse backward will make your character look down. Hit W to move forward. Hit S to move backward. Hit A to move to left. Hit D to move to the right. A navigation arrow will guide you to the goal of your current objective. It is a white arrow with the length of your current location to your objective. It is in the top of screen. In every mission, there is an objective. Follow the rules to go further.  In the start of the game, the first objective you will see is to “Go to the Library.” Move your cursor forward to get in there. Follow every objective to accomplish your mission. You will encounter these walking dead throughout your mission.  Change your combat by keying letter Q. Close combat using melee weapon, like wrench, knife, crowbar, or chainsaw, is when the zombie is not aware of your presence. Just move closer to the opponent, and it will automatically attack them. Range combat using a weapon with ammo supports, such as handgun, shotgun, etc., is when the zombie will closely attack you. Aim the crosshair at the zombies, and it will automatically attack them. You can change your controls in Setting if you prefer tapping the left click of the mouse when firing. Before using these hotkeys, assign the items to the numbers first.  In your journey, you will find Ammo Box. Replenish your ammo by aiming the crosshair to the box.

Summary:
Move your mouse to look around. Use the keys W, A, S, D to move. Follow the navigation arrow. Follow the rules of the mission. Kill zombies. Click the numbers 1, 2, 3 to use items such as grenade, painkillers, or mine. Click “Tab” to exchange range combat weapons. Replenish your ammo.