Objectives are the most important part of any Objective mode map. They determine how the gameplay should flow as well as setting winning / losing conditions for players. There is no limit on the number of objectives that can be placed in a map, but you should try to reduce it where possible to avoid clutter. It is important to note that there can only be one active objective at any given time. If you want to create complex 'multi-part' objectives you are often better off using multiple conditions inside a single objective than creating multiple different objective actors. Another thing to keep in mind is that objectives are always the same for all players connected to a server. You cannot assign one player an objective that is different from someone else's. Outside of these limitations, there are very few things you can't do with Objectives. They are highly configurable and capable of producing some very complex and interesting gameplay scenarios.
Placing your First Objective
Open the Actor classes browser and navigate to StoryObjectiveBase. Expand it and you should see 'KF_StoryObjective'.
Select it and right click anywhere in your map with solid ground. You see the option to 'Add KF_StoryObjective'. Select this option and you should now see a green icon with a checkmark in the viewport.
Objective Naming
Now that you have an objective in your map you need to give it a name. Select the objective and press F4 to open it's property menu. Click on 'Objective_Settings' from the list of collapsible categories so that it expands. Enter a name for your objective here. it can be whatever you want, but it helps to have it be relevant to what you want the players to do to complete it. i.e the Bloat bile objective in KFO-Frighyard is named 'CollectBloatBile'.
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Objective Ordering
Now that your objective has a name, the next step is to let your map how the order in which it should be given to players. To do this, we are going to add it to a list in the level properties.
Press F6 to bring up the level properties window for your map. Expand the rollout titled 'Rules_Objectives' and select 'Add' next to the StoryObjectives array. This will produce a blank field where you should enter the name that you came up with for your first objective. The order in which you enter objective names in this array is very important. Index [0] of the array will always be the position of the first objective you want players to complete. Subsequent indices in the array denote future objectives in the order you wish them to be completed.
Objective Conditions
Now that you have added an objective to your map, it's time to add some conditions to it.
Conditions are pieces of logic which let the Objective know when it should be considered 'complete', and whether the outcome was successful, or whether players failed to accomplish their goals.
As with objectives themselves, there is no limit to the number of conditions an objective actor may contain. However, unlike objectives, conditions have replicated properties which means there could be network performance issues if you decided to have a huge number of conditions active at the same time. Use your best judgement. In general, the fewer conditions you use, the less performance overhead there will be.
Conditions are broken up into different broad 'types'. As of the Halloween 2013 update , these are all the 'official' condition types you can use in your map: