At first in Necronator 3 you will only have some gold which you can use to build soldiers. As soon as you have some available units, you can use your mouse to select them and move them towards your enemies. You will have to protect your castle at the same time, so make sure that the coast is clear by moving the screen around with the WASD keys. If you kill a few enemy soldiers in Necronator 3, you will receive extra gold. Keep an eye on your resources and you might have enough money to create more powerful units which will make your job even easier. Once you destroy the enemy castle, you will see a few statistics about the battle, including the number of units you lost and the total gold earned. Between attacks, you can manage your army and purchase upgrades. You need to take a good look at what types of spells you can purchase because this is where your fate will be decided. If you don't pick the right upgrades, your next opponents might be too powerful and you will lose your castle.
Necronator 3 is a very advanced strategy game in which every move counts. You need to act and make the right decision quickly in the middle of the battlefield and keep your head leveled between battles when you have to purchase new equipment.