What goes into a game?
When you play a game, you probably are able to identify what needs to go into a game. In a simple PC shooting game example, when you press the left mouse button, the gun triggers. You see bullets flying, hear the sound of the gun and look around to see if you have shot anything. If you did hit something, for example, a wall, the target receives some form of damage.
As a game creator, we need to learn breakdown what we see in a game to figure out what we need for a game. A simple breakdown without going into too much detail: link the mouse click to the firing of the bullets, play a sound file that sounds like a gun firing, display sparks (termed as particle effect) near the barrel of the gun and the target shows some visible damage.
Bearing this example in mind, try visualizing and breaking any game down into its fundamental components. This will greatly help you in designing and creating a game level.
There is a lot going on behind the scenes when you are playing a game. With the help of Unreal Engine, the interaction of the many components has been designed and you will need to customize it for your own game. This is a huge time saver when you use an engine to create a game.