We have been talking about players' trust, motivation, immersion, rewards and punishments, and mechanics. Each one of these fragments is put together inside our levels, so it is our job to balance everything in order to keep players' attention and belief.

With this in mind, our level has to fit with our characters, both player and NPC, and the elements that are present have to be appropriate. This congruence is in art style, sound effects, and behaviors. So, do you mean that if the level aesthetics are the same as the characters and the objects, and these have the appropriate reactions, that would mean I created the perfect level? Sorry, my friend, but no, that is just a small part of it.

Appropriate behaviors also mean that characters in the game must act according to their history and the world environment. We can't be playing a fantasy medieval game and, when we get to talk with the King of the Realm, he says to us, Yo, dawg, I heard you like killing some dragons. So, you wanna kill me some dragons so we can live in peace? That would be really weird; please, I beg you, don't you dare.

Once we have worked hard to get every piece balanced, we must face the most difficult challenge; we have to create something self-explained, entertaining, and challenging.

Instructions in a level are critical for anyone who chooses to play our game. These instructions can be shown in two ways: either we can choose to play a tutorial with a heavy User Interface (UI) showing buttons and texts, which is the classic way, or we can choose to give players instructions while they are experiencing the game:

Many level designers believe in using this second option, because it sticks in the players' minds. The first thing we do in Mario Bros is smash a brick, step on Goompa and grab a mushroom, so this means that after playing for 15 seconds, we know the basics for the rest of the game; no gameplay mechanic will surprise us, at least for several levels more:

Whenever we choose to show a basic concept, it is always good to encapsulate the situation as much as possible. We have to try to let the player face that unique situation and learn from it, in a logical way, not being influenced by any other external effect that might change the final outcome.

Entertainment is usually related to gameplay and the story. We must try to think of game mechanics that belong in our world, and its history. Don't forget that, usually, through the game we will be telling a story, so if we leave this out, at some point, players will lose interest in the game, because they will feel that nothing they do influences the world they are in. The player has to be continually looking forward to the next level, the next piece of the story.

So, don't hesitate to give a tip in the form of a bar encounter, a photo we have been given by a treasure hunter, a story told by a local musician, or any other way that comes to mind!

How do we become better at this? Read books and stories, play any type of game, then play the same genre and subgenre of game we want to create, type down everything we like and everything you hate about those, and try to find better ways and answers. But, don't forget, our game has to be unique—the player is not looking for the next Shadow of the Colossus; they have Shadow of the Collosus for that, so give them something different, innovative, and new.

People buy games because they want to be challenged, of course in many different ways, depending on the game. The challenge is related to the difficulty we add at certain points of the game; this can be provided by puzzles, by enemies who last longer and hit harder, by adding more enemies, or by strategy planning.

Be careful, as I mentioned before, we have to keep in mind players' frustrations, so be sure to balance every critical moment of our game. Frustration leads to quitting.

In order to avoid this, it is always a good practice to present small challenges at first, and only then give the player a big challenge, which will require different skills learned on previous challenges. Also, taking into account player progression, we can choose to present a certain situation to a player they can't beat at that time, in order to show them that, in the near future, they will learn a new skill, and the user will then look forward to it. With this, we also avoid using many different gameplay mechanics all at once, at the beginning, which may create the impression of a complicated controller setting. Unity 2D Game Kit boss fight is as shown follows:

This level is difficult for someone who hasn't played the game. This is why we always play a few level, before finally facing a boss. The same goes for the following screenshot, where the player is facing two bosses at once in an epic finale: