Now we will talk on the level design. It is a very important part inside the design tasks, as we have already said in the previous modules. It is key to determine the experience we want to provoke. In fact, we mustn't forget the fact that he player only perceives the game through the different levels. He doesn't have a general vision of the game, as designers or developers do. Through levels creation, an important part of the gameplay is designed and implemented in the engine. So, this task inherits a lot of characteristics from the gameplay design, such as the fact of being a very artistic work that requires a lot of adjustment and retouching. Each level can be conceived as a mechanics distribution, built to provoke the player a concrete experience. Here we talk on levels as a general term but we could also use other terms used to divide video games such as missions, phases, worlds, episodes, arenas, etc. The elements to take into account while designing the level are the following ones: scenario; mechanics regarding the scenario; character mechanics; enemies' mechanics; objectives, challenges and puzzles; dynamics and strategies; events and information. Let's begin with the scenario. In this section we are interested on the game space basic characteristics, especially regarding their size and shape. The scenario's general proportion is very important, as it determines the size of all the elements and their relationship. Usually the scenario's proportion is limited depending on the expected played time. The space's volumetry and shape is also important as it influences on how the player perceives the space and eases -or not- his orientation. Orography is also very influent, as it's not the same a plain zone than one with many slopes, affecting in example the vision distance. We must also take into account the different height levels, such as a building's many floors or the holes that delimit zones in which the character can fall. The spaces division is especially relevant. In example, a house or a castle divided in many rooms. In the same way, we must design the entrances and connections between these zones in which the level is divided. Other elements linked to the scenario are the following ones: doors, windows, etc. which are used as an access to zones inside the scene; fences, obstacles which are a barrier to limit movement between zones; trampolines, catapults, teleport, which are used to fasten the movement in a specific way; platforms, which are parts of the scenario with an own identity, some with many behaviors such as self-destroying or moving; kinds of surface, from water, lava, ice or vines to climb buildings; generation points which are a spacial reference to generate items or other elements, such as the point where the character goes back to when he dies, spawn points; event points which are a reference for certain events, such as the lock where we have to put the key in to pass the level. To design the level we must also take into account some aspects related to the character's mechanics. The level design must depend on these mechanics. To begin we must decide the mechanics the character has available in each level. Usually not all the character's mechanics are available from the beginning, but they are unlocked during the game. From that point we adapt the own scene, the enemies and the challenges so that they can be passed with the available mechanics. The boosting elements such as weapons or special powers, are another way of playing with the character's mechanics in each level, as it's the level's designer the one who decides when they are available and when they aren't. In example, Super Mario Bros' flower can be picked up only in certain points of certain levels. Similarly, we must take into account the enemies' mechanics, In first place we have to decide the enemies' position on the terrain or the scenario. This involves concreting at the same time the amount of enemies, which obviously alters gameplay a lot. Also there are certain types of behaviors in some enemies which depend a lot on the scenario in which they are, such as routes or guard patrols. This kind of behavior must also be concreted when making the level design. Finally, we must determine if the enemies make position structures creating formations or waves. In example, they might attack in groups of 3 during 5 waves. This can include mixing different enemies in the same group to give them more variety. Another relevant aspects are the ones which refer to determining the objectives, challenges and puzzles for each level. This basically takes us to specifying what the player has to do in each point of that level. The scenario's configuration and the enemies distribution are a basic challenge type the player needs to pass. Also we must concrete the higher level objectives and challenges, which are part of the requirements to pass the level, such as getting to a certain point on the scenario or taking a special object. Each level's design is the building of many challenges built ones inside the others so that the player passes them. Each level must be created playing with the criterion of difficulty and player's ability. The level must be hard so that it is a motivating challenge, but it must also fit the player's ability so that he doesn't find it too complicated and ends up frustrated.