The goal of LeviTank2D depends on the level. Most levels will be beaten once you reach the end goal (shown to the left), which will be located somewhere in the level, and some levels will require that you destroy all enemies on the field. In some levels (though you cannot make this on the level editor), there are also special conditions for winning or loosing; you may need to keep the enemy away from something, protect a particular unit, destroy a particular unit, or perhaps something else.
To shoot, you must aim with your cursor, and click to fire. For most weapons, you will need to click each time you fire a shot, while others are fully automatic. In the upper Left Corner of your screen you will see the name of the weapon you are using next to a number that indicates how many bullets you have left for this gun aside from the ones in your clip. Below that is a set of vertical bars that represent the bullets in the clip you are shooting from. Once you run out, you will have to wait for the gun to reload. When the clip runs out of ammo, the gun will automatically reload, but if you want to reload before hand you may press the 'c' key. Also, if you run out completely, or just want to change weapons, you may be able to switch to a different gun by pressing the 'e' key (assuming you have ammo for another gun). If you need more ammo, look for ammo on the ground . Ammo will drop from all players once they are destroyed, and can be used to refill different weapons depending on what kind of ammo it is. Some weapons also have a scope on them that will move your view toward your target when active. To use the scope on these weapons, press and hold the right mouse button.
Being in the middle of a war means that you will encounter many enemies. You can identify enemies three ways: they all have orange markings, they will be shooting at you, and your allies will be shooting at them.
In LeviTank, you're not alone. You will often have allies who will fight for you and interact with you. If you ever need their help, just press 'R' and a yellow square will appear in the upper left corner of your screen, indicating that your allies will follow you. Simply press 'R' again to turn it off.