= How to create Orxonox Levels =
[[TracNav(TracNav/TOC_CC_Tut)]]

It it recommended to first have a look at some of the existing levels. In the single player menu at the tab all to the right you find a complete list of all orxonox levels.

== Create the basic file ==
 1. Go to the folder __../data/levels__. The level files ending with .oxw are simple XML files and can be opened with any text editor. Each level file stored in this folder can be selected later in Orxonox.
 2. Copy „empty_level.oxw“ and paste it again in the folder.
 3. Rename the copy. Try to use a name that sounds good. Avoid whitespace – use „_“ or CamelCase instead.
 4. Open your level with your favourite editor.

== About XML ==
XML is a description language that looks similar to HTML. We use '''tags to describe objects''':
{{{
#!xml
<templates>                               <!-- Opening tag 1 -->
    <Template link=lodtemplate_default /> <!-- Opening and closing tag 2 at once -->
</templates>                              <!-- Closing tag 1 -->
}}}
							
A '''<tag>''' can contain several '''attributes'''. An attribute is the place where '''a value is set'''.
{{{
#!xml
<Light type=directional position="0,0,0" direction="0.253, 0.593, -0.765" diffuse="1.0, 0.9, 0.9, 1.0" specular="1.0, 0.9, 0.9, 1.0" />
<!-- Quite a lot of attributes. -->
}}}
The syntax is '''attribute=“value(s)“'''. If only one value is set, the quotation marks are not necessary.

Tip: XML files do not have to be compiled. If you changed a level file (and didn't forget to save it), you simply have to reload the level to view the changes. If your level doesn't load have a look at the terminal by pressing [alt] + [tab].

== What it's all about ==
By describing a level via XML you actually '''add C++ objects''' to the level. Each tag starting with a capital letter refers to a class that contains a XMLPort function. In order to understand better what a certain tag is doing it is recommended to read the corresponding source files.
Example: The <Light> tag shown before refers to the [http://www.orxonox.net/browser/code/trunk/src/orxonox/graphics/Light.h light class].

== First steps ==
 1. In the first tag in your XML file, define the level's '''name''' in the menu. The '''description''' will be displayed in the level selection menu when a player hovers his mouse over your level's "name". '''screenshot''' should be a *.png image placed in the __data_extern/images/levelpreviews__ folder.
{{{
#!xml
<LevelInfo
 name = "Teambase Match"
 description = "Fight for the bases."
 tags = ""
 screenshot = "teambase.png"
/>
}}}
 2. Decide wether you create a level for a specific '''gametype''' or a '''single player mission'''. The gametype is set in the <Level> tag.
{{{
#!xml
<Level
 gametype = "TeamBaseMatch"
>
}}}
 3. Set the level's backgroud (skybox). The skybox is an image of what you can seen on the horizon. You can add an new skybox by changing the corresponding parameter:
{{{
#!xml
<Scene
    ambientlight = "0.5, 0.5, 0.5" 
    skybox       = "Orxonox/Starbox" 
>
}}}
Possible values for skybox are:
|| "Orxonox/Starbox" || "Orxonox/skypanoramagen1" || "Orxonox/skypanoramagen2" || "Orxonox/skyBoxMoreNebula" ||

== Basics ==
 * '''Worldentity''': Point in space with orientation ( ~point with a vector attached to it).
  * '''Static Entity''': Worldentity with a fixed position and fixed orientation.
  * '''Movable Entity''': Worldentity that can rotate or move constantly.
  * '''Controllable Entity''': Completely freely movable point. Usually steered by a controller.
 * '''Model''': Each visible 3d-Object. A model consists of a mesh (the form) and a material (the surface colouring).
 * '''Collisionshape''': A Collisionshape is the physical representation of a model. Currently collisionshapes only have the form of a sphere, cube/ashlar, cone or plain. For StaticEntities the collisionType is „static“. Movable Entities have the collisionType "dynamic". At the moment static collisionshapes do not provide a shield against bullets. The collision of projectiles is only detected by dynamic collisionshapes. Another significant difference: If you collide with a static collisionshape, you'll be pushed away. If you collide with a dynamic collisionshape you'll push the dynamic collisionshape and it's movable entity away.
Or even more vivid - if you place two movable entities with collisionshapes too close together, such that the collisionshapes ovelap, they'll burst apart. If both objects are static they will stay as they are, although their collisionshapes overlap.


== Worldentity + Model + Collisionshape = adding objects to the level ==
{{{
#!xml
<StaticEntity position="0,-10000,0" direction="0,-1,0" collisionType=static mass=100000 friction=0.01 >
    <attached> 
        <Model position="0,0,0" mesh="cube.mesh" scale3D="10000,10000,1000" /> 
    </attached> 
    <collisionShapes> 
        <BoxCollisionShape position="0,0,0" halfExtents="10000,10000,1000" /> 
    </collisionShapes> 
</StaticEntity>
}}}
The StaticEntity defines the model's place and orientation (and some other values). The Model (a cube) is attached to the StaticEntity. With the proper sized collisionshape attached to the StaticEntity you have a "solid" cube. Without a collisionshape, the cube wouldn't be solid and your spaceship could just fly through it. This exampe is quite useful, since you usually can't see a collisionshape's size. If you combine an invisible collisionshape with a fitting model you can see where a collisionshape is for testing purposes. In this special case both the '''scale3D''' and the '''halfExtents''' parameters are identical.

== MovableEntity - Let's get the world moving ==
Worldentities can be attached to other worldentities. If you want a model to move in circles, you can create a MovableEntity that rotates and a StaticEntity attached to it. The model that should be rotating is attached to the StaticEntity.
{{{
#!xml
<?lua
    dofile("includes/CuboidSpaceStation.lua")
  ?>
<!-- ----------------Rotating SpaceStation--------------- -->
<MovableEntity position="1,1,1" rotationrate="-4.5" rotationaxis="0,0,1">
    <attached>
        <StaticEntity position="-2500,0,0" yaw=90 pitch=90>
            <attached>
                <?lua
                  createSpaceStationPar(0,2,1,2,1,4,1,50)
                ?>
            </attached>
        </StaticEntity>
    </attached>
</MovableEntity>
}}}
Note that in this example the Model is created by a lua script that is called in a lua tag. Lua is a scripting language that is a very powerful tool for level design.

== Models ==
A level depends on its models. All finished models are stored in __../data_extern/models__. If you want to view most models in the '''Gallery''' level.
At the moment we have several asteroids, spaceships, a satellite, two different space stations and some smaller models.

== Spawnpoints ==
A Spawnpoint is the '''entrance point''' for controllable entities (spaceships). Without a spawnpoint no level can work!
{{{
#!xml
<SpawnPoint team=0 position="-200,0,0" lookat="0,0,0" spawnclass=SpaceShip pawndesign=spaceshipassff />
}}}
You can define which kind of spacecraft a player/ bots can use. Additionally the corresponding template has to be included:
|| '''pawndesign''' || '''include()''' || '''additional information'''||
||spaceshipassff||"templates/spaceshipAssff.oxt"||default spaceship - equipped with rockets||
||spaceshippirate||"templates/spaceshipPirate.oxt"|| ||
||spaceshipswallow||"templates/spaceshipSwallow.oxt"||fast, nice design||
||spaceshipHtwo||"templates/spaceshipH2.oxt"|| ||
||spaceshipghost||"templates/spaceshipGhost.oxt"||stealth aircraft ||
||spaceshipHXY||"templates/spaceshipHXY.oxt"||||
||spaceshipHXYSL||"templates/spaceshipHXYSL.oxt"|fast||
||spaceshipTransporterSL||"templates/spaceshipTransporterSL.oxt"||slow transporter||
||spaceshipTransporter||"templates/spaceshipTransporter.oxt"||slow transporter, equal to SL version||
You find all spaceship files in __../data/levels/templates__. The first entry in a file reveals the pawndesign:
{{{
#!xml
<Template name=spaceshipghost> .
}}}
If the level is designed for several teams you have to use team spawn points.
{{{
#!xml
<TeamSpawnPoint team=0 position="1000,0,0" lookat="0,0,0" spawnclass=SpaceShip pawndesign=spaceshipassff/>
}}}

== [http://www.orxonox.net/doxygen/classorxonox_1_1_pickup_spawner.html Pickups]  ==
Pickups give a player a temporary bonus when collecting it. Bonuses are invisibility, health, boost,  shield, a drone, ...
 1. Include the pickupsRepresentationTemplates. This include should be somewhere between the LevelInfo and the opening Level tag.
{{{
#!xml
<?lua
    include("templates/pickupRepresentationTemplates.oxt") 
 ?>
}}}
 2. Include the pickups. This include should be after the opening Scene tag.
{{{
#!xml
<?lua
    include("includes/pickups.oxi") 
 ?>
}}}
 3. Add a PickupSpawner. An invisible device that puts pickups in the level.
{{{
#!xml
<PickupSpawner pickup=smallshieldpickup position="-25,-25,-125" triggerDistance="10" respawnTime="5" maxSpawnedItems="10" />
}}}
'''Pickupspawner - attributes''':
 * '''triggerDistance''': Distance to collect the pickup. The larger the triggerDistance, the easier it is to get the pickup.
 * '''respawnTime''': After respawntime seconds a new pickup will appear, if the pickup had been collected.
 * '''maxSpawnedItems''': After maxSpawnedItems no further pickup will appear.
'''Pickups - have a look at pickups.oxw''':
|| <ShieldPickup template=hugeshieldpickup /> ||<ShieldPickup template=mediumshieldpickup />||<ShieldPickup template=smallshieldpickup />||
||<HealthPickup template=crazyhealthpickup />|| <HealthPickup template=hugehealthpickup /> ||<HealthPickup template=mediumhealthpickup />||<HealthPickup template=smallhealthpickup />||
|| <SpeedPickup template=hugespeedpickup /> || <SpeedPickup template=mediumspeedpickup /> ||<SpeedPickup template=mediumspeedpickup />||<SpeedPickup template=smalljumppickup />||
|| <InvisiblePickup template=hugeinvisiblepickup /> ||<InvisiblePickup template=mediuminvisiblepickup />||<InvisiblePickup template=smallinvisiblepickup />||
|| <MetaPickup metaType="use" /> || <MetaPickup metaType="drop" /> ||<MetaPickup metaType="destroy" />||<MetaPickup metaType="destroyCarrier" />||
|| <DronePickup template=dronepickup /> ||<PickupCollection template=triplehealthspeedinvisibilitypickup />||

== Billboards ==
Pickups are represented by billboards. Billboards are 2D images that are always facing the viewer. A 2D circle image seems to be a 3D sphere. E.g. The blinking lights on the assff wing are realized via billboards. Example of a static light sphere:
{{{
#!xml
<MovableEntity position="0,0,0">
    <attached>
        <Billboard position="100,0,0" material="Examples/Flare" colour="0, 0, 1" scale=1/>
    </attached>
</MovableEntity>
}}}

Billboard in action:
 * Mark points of interest with a light. Maybe this will attact the player.

Have a look at "theTimeMachine.oxw" to see some further billboards in action.

== ForceFields ==
ForceFields push the player in a certain direction if the ForceField was triggered.
{{{
#!xml
<ForceField position="-500,0,500" direction="0,0,-1" diameter=500 velocity=2500 length=750 />
}}}
As you maybe already have noticed - you don't have the ForceField to be attached to a Worldentity.

ForceField in action:
 * Place the ForceField next to the Spawnpoint to give the player extra boost when entering the level.

Have a look at "asteroids.oxw" and "theTimeMachine.oxw", to see how to make ForceFields visible in the level.

== SpaceBoundaries ==
If you want to restrict the position of pawns to certain areas, space boundaries may be useful. They are commonly used to avoid that a Pawn leaves the level.
{{{
#!xml
<SpaceBoundaries warnDistance="1" maxDistance="200" showDistance="150" reactionMode="0" healthDecrease="0.9" position="0,0,0"/>
}}}

Have a look at "myTestLevel.oxw" and "SpaceBoundaries.h", to see how space boundaries work in detail.

== Portals ==
Portals allow to teleport through space.
First you need to place at least two PortalEndPoint. Give each end point a unique id using e.g. id=1. Then you need the PortalLink class to define which PortalEndPoint is connected to which other PortalEndPoint.
The attribute target of a PortalEndPoint may be used to restrict the classes that can use the PortalEndPoint. By default all Pawn instances can use it. By typeing target="MobileEntity" all MobileEntity instances can use the PortalEndPoint.
The templates in the example below only hve the purpose to make the end points visible. Use the design attribute of a PortalEndPoint to automatically apply the specified template to it.
{{{
#!xml
<Template name=PortalDefault>
    <PortalEndPoint>
        <attached>
            <Billboard material="Portals/Default" />
        </attached>
    </PortalEndPoint>
</Template>

<Template name=PortalBig>
    <PortalEndPoint>
        <attached>
            <Billboard material="Portals/Big" />
        </attached>
    </PortalEndPoint>
</Template>

<PortalEndPoint position="0,0,0" id="1" distance="40" target="Pawn" design="PortalDefault"/>
<PortalEndPoint position="-100,0,0" id="2" distance="40" target="MobileEntity" design="PortalBig"/>
<PortalLink fromID="1" toID="2" />
<PortalLink fromID="2" toID="1" />
}}}

Have a look at "Portals.dox", "portals.oxw", "PortalLink.h" and "PortalEndPoint.h", to see how portals work in detail.

== Lua ==
Lua is the scripting language we use in our levels. At the beginning of the file templates for spaceships, the hud and more are loaded. What lua does in this context is editing the XML file and inserting the concerning XML (of the spaceships, hud, ..) before the level is loaded. That's why you cannot rely on the line numbers displayed when an error occurs, since before loading lua changes the file.

A quick overview over Lua: [http://tylerneylon.com/a/learn-lua/ Learn Lua in 15 minutes]

What lua can do:
 * load external skripts: for example the cuboid spacestation.
{{{
#!xml
<!-- First, the script has to be included (only once). -->
<?lua
    dofile("includes/asteroidField.lua")
?>

<!-- Usage: Creates an asteroid belt -->
<?lua
     asteroidBelt(20000, 0, 13000, -48, -34, 70, 100, 200, 22000, 20000, 500, 1)
?>
<!-- asteroidBelt(centerX, centerY, centerZ, yaw, pitch, segments, minSize, maxSize, radius0, radius1, count, fog) -->
}}}

 * Create a bunch of objects (depending on the index i). Whatever is placed within those lua tags will be created several times.
{{{
#!xml
<!-- A for loop. The index i starts from 1, is increased up to 10 by adding +1. -->
<?lua
for i = 1, 10, 1 do
?>
    <SpawnPoint team=0 position="<?lua print(i*100 + 50) ?>,0,0" lookat="0,0,0" spawnclass=SpaceShip pawndesign=spaceshipassff />
<?lua end ?>
}}}
 Note that '''<?lua print(i*100 + 50) ?>''' directly inserts the calculated value when the level is loaded.

 * Randomized values, sinus, cosinus and more. (Via sinus and cosinus circular shapes can be created easily. The randomization changes your level's appearance whenever it is reloaded.)
{{{
#!xml
<!-- Positioning objects in a circle -->
<?lua
max = 16
for i = 0, max, 1
do
    y = math.sin(i/max*6)*750
    z = math.cos(i/max*6)*750
?>
    <StaticEntity position="<?lua print(y) ?>,0,<?lua print(z) ?>" scale="<?lua print(math.random() * 10 + 5) ?>" collisionType="static" >
<?lua end ?>
}}}


== Triggers && Events ==
Example: ../data/levels/events.oxw

So far your level design is static. Everything is placed in the level, when it is loaded (except the spawned objects) and doesn't change its behaviour once loaded. Via the trigger/event system you can make the level react on what the player does.
A trigger is like a button. When you activate it an event is created. This event can change the status of objects.
This way objects can be activated/deativated and be made visible/invisible.
=== Distance Triggers ===
{{{
#!xml
<DistanceTrigger name="flying1" position="800,700,600" target="Pawn" distance=10 stayActive="true" delay=6/>

<SimpleNotification message="Let's fly to the blinking light." broadcast="true">
    <events>
       <trigger>
           <EventListener event="flying1" />
        </trigger>
    </events>
</SimpleNotification>
}}}
'''DistanceTriggers''' are activated, when the target (e.g. a pawn, a spaceship, ...) is close enough to the distance trigger (defined via "'''distance'''"). The '''stayActive''' attribute keeps the switch activated once triggered - the event can only be created once. The name '''flying1''' is needed in order to catch the event, when the trigger was activated. The '''SimpleNotification''' is sent to the player when the trigger is activated. Note that the trigger is activated with a delay of 6 seconds.
The problem of distance triggers is that you have to rely on that the player is actually activating it as intended. Try to attract the player by using bliking billboards, pickups to reward the player, ... and make the radius large enough such that the player can hardly miss it.
Another problem might be that the distance trigger is triggered by another Pawn/Spaceship/... (whatever is specified as target). To exclude certain objects to activate the trigger or to only allow a specific object to activate the trigger, the '''DistanceTriggerBeacon''' was created:

{{{
#!xml
<!-- This trigger CANNOT be triggered -->
<DistanceTrigger position="10,-202, -42" distance="800" target="Spaceship" beaconMode="exclude" targetname="stupidSpaceship" name="dockMe"/>

<!-- By this Spaceship -->
<SpaceShip position  = "10,-202, -42" ... > 
    <attached>
        <DistanceTriggerBeacon name="stupidSpaceship" />
        <Model mesh="HydroHarvester.mesh" mass=10 position="0,0,0" scale=50 />
    </attached>
</SpaceShip>
}}}



{{{
#!xml
<!-- This trigger can ONLY be triggered -->
<DistanceTrigger position="10,-202, -42" distance="800" target="Spaceship" beaconMode="identify" targetname="coolSpaceship" name="dockMe"/>

<!-- By this Spaceship -->
<SpaceShip position  = "100,300,900" ... > 
    <attached>
        <DistanceTriggerBeacon name="coolSpaceship" />
        <Model mesh="HydroHarvester.mesh" mass=10 position="0,0,0" scale=50 />
    </attached>
</SpaceShip>
}}}

=== Other event sources ===
{{{
#!xml
<!-- When this Pawn is destroyed -->
<Pawn health=30 position="0,300,0" direction="0,-1,0" collisionType="dynamic" mass="100000" name="kaboom" radarname = "Box 1">
    <attached>
        <Model position="0,0,0" mesh="crate.mesh" scale3D="3,3,3" />
    </attached>
    <collisionShapes>
        <BoxCollisionShape position="0,0,0" halfExtents="15,15,15" />
    </collisionShapes>
</Pawn>

<!-- an event called "kaboom" is created -->
<SimpleNotification message="Right click on the next target." broadcast="true">
    <events>
        <trigger>
            <EventListener event="kaboom" />
        </trigger>
    </events>
</SimpleNotification>
}}}

=== Advanced Triggers ===
A triggers can be combined in several ways:
 * A trigger can have a trigger. The outer trigger can only be triggered, after the inner trigger was triggered:
{{{
#!xml
<DistanceTrigger name="navigationend" position="0,0,0" distance=950 target="SpaceShip" stayActive="false" delay=1.1>
    <DistanceTrigger name="flying4" position="-900,640,600" target="Pawn" distance=60 stayActive="true" delay=1/>
</DistanceTrigger>
}}}
In "missionOne.oxw" the order the player destroys the boxes should not influence the order the messages arrive, what the player should do next after having destroyed such a box.
The solution to this problem is naming each box as "box". When the fist box is destroyed, the innermost EventTrigger listens to the event "box" and creates the "boxtrigger1" event in return. Similarly, when the next box is destroyed later, the innermost EventTrigger is not triggered again, as it stays active. That way, the next EventTrigger is triggered that way.
{{{
#!xml
<EventTrigger name="boxtrigger4" activations="1" stayactive="true" delay=0.1>
  <events>
    <trigger>
      <EventListener event="box" />
    </trigger>
  </events>
  <EventTrigger name="boxtrigger3" activations="1" stayactive="true" delay=0.1>
    <events>
      <trigger>
        <EventListener event="box" />
      </trigger>
    </events>
    <EventTrigger name="boxtrigger2" activations="1" stayactive="true" delay=0.1>
      <events>
        <trigger>
          <EventListener event="box" />
        </trigger>
      </events>
      <EventTrigger name="boxtrigger1" activations="1" stayactive="true" delay=0.1>
        <events>
          <trigger>
            <EventListener event="box" />
          </trigger>
        </events>
      </EventTrigger>
    </EventTrigger>
  </EventTrigger>
</EventTrigger>
}}}

 * A trigger can have several triggers that are combined with boolean logic:
{{{
#!xml
<Trigger name="duball2" mode="and" stayactive="true">
    <EventTrigger activations="1" stayactive="true" delay=4 >
       <events>
          <trigger>
             <EventListener event="duball1" />
          </trigger>
       </events>
    </EventTrigger>
    <EventTrigger activations="1" invert="true">
      <events>
        <trigger>
          <EventListener event="toHydroFarmer" />
        </trigger>
      </events>
    </EventTrigger>
</Trigger>
}}}
In this case the "duball2" event triggers a message but only, if the event "toHydroFarmer" was not triggered before. This is achieved by inverting (not-operation) the "toHydroFarmer" event and combining the two corresponding EventTriggers with "and".

=== What events can do ===
 * Making objects (in)visible:
{{{
#!xml
<DistanceTrigger name="switchBillboards" position="-900,640,600" target="Pawn" distance=70 stayActive="true" delay=1/>

<!-- switchBillboards makes this billboard INVISIBLE -->
<BlinkingBillboard position="-900,640,600" frequency=0.6 amplitude=3 material="Flares/lensflare" colour="1,1,0.05">
   <events>
      <visibility>
        <EventTrigger invert=true>
          <events>
           <trigger>
             <EventListener event=switchBillboards />
           </trigger>
         </events>
        </EventTrigger>
      </visibility>
   </events>
</BlinkingBillboard>

<!-- switchBillboards makes this billboard VISIBLE -->
<Billboard position="-900,640,600" amplitude=1 material="Flares/lensflare" colour="0,0.8,0.1">
  <events>
    <visibility>
        <EventTrigger>
          <events>
            <trigger>
              <EventListener event=switchBillboards />
            </trigger>
          </events>
        </EventTrigger>
    </visibility>
  </events>
</Billboard>
}}}
 * (De)activating objects. In "missionOne.oxw" if the player dies after having taken the spacecruiser, the player should be respawned with the other spaceship at a sensible place. This is managed by deactivating the old TeamSpawnPoint and activating a new TeamSpawnPoint.
{{{
#!xml
<TeamSpawnPoint team=0 position="2000,1500,-1500" direction="-1,-1,1" spawnclass=SpaceShip pawndesign=spaceshipspacecruiser>
    <events>
        <activity>
            <EventListener event="attack" />
        </activity>
    </events>
</TeamSpawnPoint>
}}}
{{{
#!xml
<SpaceShip position="3000,-4000,4000" lookat="-1300,-600,900" name="attacker"visible="true">
    <events>
        <visibility>
            <EventListener event="ondock" />
        </visibility>
    </events>
    <templates>
        <Template link=spaceshippirate /> <!--spaceshipTransporter -->
    </templates>
    <controller>
        <WaypointPatrolController alertnessradius=3129 team=1 active=false>
            <waypoints>
                <Model mesh="cube.mesh" scale=0 position="-1300,-600,900" />
                <Model mesh="cube.mesh" scale=0 position="0,0,0" />
            </waypoints>
            <events>
                <activity>
                    <EventListener event="attack" /> <!-- activates enemies-->
                 </activity>
            </events>
        </WaypointPatrolController>
    </controller>
</SpaceShip>
}}}
 * Executing '''ConsoleCommands''' (= executing code):
{{{
#!xml
<!-- End the Mission (success) -->
<Script code="Mission endMission true" onLoad="false">
    <events>
        <trigger>
            <EventListener event=endOfLevel />
        </trigger>
    </events>
</Script> 
}}}
The ConsoleCommand "'''Mission endMission true'''" gets executed, which will end the mission and make the player accomplish the mission.

==== How to find out more console commands ====
Open the in-game console and press [Tab] (command completion) to find out which console commands already exist. Note that if there is no shortcut, the command completion only reveals the command word by word - you have to specify the class and press tab again to see which commmands are created in a specific class and repeat this process again to see which argument is needed for a specific ConsoleCommand.

== Quests ==
Example: ../data/levels/quests.oxw


== Templates ==


== Best Practices ==
 * Make objects that belong to each other be close to each other. Ideally the trigger is placed right before the object listening to the trigger's event. Use comments to mark groups that belong together.
 * As a level designer, you are a story teller. Always tell your story in several ways, since a regular user will miss some information and yet should know what is going on. E.g. send a message that some traitors have turned their flags and now cooperate with the enemy. Make sure that the concerning spaceships are re-coloured in the radar & HUD. Let one of them fly to the player and attack. (Show, don't tell.)
 * Reward the player when he is doing something right and correct his mistakes early, if he is doing something wrong.
 * Let someone else play-test your level. Where does the player get stuck? What is too easy / too hard?
 * Have you discovered a missing feature? Create a new ticket on orxonox.net.

== Trouble Shooting ==
Housten, ...
 * the level does not show up in the level list. This looks like an XML error.
 * the console shows that there is an XML error. First of all: do not trust the error's line number, as the lua scripts will modify the level files when they are loaded.
  * Save your file and commit it. If you are lucky, your modifications since the last commit are rather small and thus you might easily spot the error when looking at the diff. (Open the Timeline on orxonox.net and open your commit.) 
  * Undo the last edits and save the file. If the error does not show up, commit again. Now you should be able to spot the error.
  * Start uncommenting parts of the level (everything you created after the SpawnPoint) and regularly check if the error is gone. If the error does not show up, you just uncommented the error.


== Content from External Sources == 
When designing a level, one often runs out of models and other content to use in the level. As your time is limited, try to get external content that matches our licences. (ideally CC-BY-SA or CC-BY or Public Domain)

 * http://www.blendswap.com
 * http://opengameart.org/
 * http://freesound.org/

Export the concerning .blend file with the OgreMesh Exporter.