As an example, I changed the event frequency in Berlin, and reduced the extinguisher strength of some units to increase th e challenge in multiplayer games.

Procedure:

• Start up World Builder
  
  • Since we only want to change some settings, it is not necessary to laod a map.
  • Instead, we open the asset browser with F11.

• Create a new project
  • Inside the Asset Browser click the bottom left button (Tooltip: Create new project).
  • Another window automatically opens. Enter a name for our project (such as berlin_difficulty_hard).
  • The new project automatically contains an asset package called content. We do not need it for this mod, but we do not delete it.
  • We create an additional asset package (Rightclick the project > Create Asset Package...) and call it gamedata. Our new project is written italic. This means it is not yet running (=active).
  • Rightclick the project (not the asset package) > enable Running Project.

• Now let's copy the files we want to modify into our project
  • Select the asset package em5\gamedata. Write specs in the searchbar. Find the file specs and rightclick it > Copy to Asset Package > "My mod" > gamedata.
  • Find and copy the file berlin_challenge_eventpools the same way.
    
  • Select your mod. Find the copied files inside. You can open them by rightclick > Open Cached Asset.

• Modifying gamedata
  • In specs i reduce the extinguisher strength of some units by half
                  "ExtinguishPower_Extinguisher": "10",      // The extinguish power of an firemen with extinguisher equipment
                  "ExtinguishPower_Hose": "15",              // The extinguish power of an firemen with hose equipment
                  "ExtinguishPower_TLF": "20",               // The extinguish power of fire department TLF vehicle
    Other stuff like the range of extinguihers can also be set
  • Next i increase the frequency and maximum number of events
                "StartWaitDurationMin": "5.0",                // Minimum time (in seconds) until the first event starts
                "StartWaitDurationMax": "5.0",                // Maximum time (in seconds) until the first event starts
                "WaitDurationMin": "30.0",                    // Minimum time (in seconds) until the next event starts
                "WaitDurationMax": "30.0",                    // Maximum time (in seconds) until the next event starts
                "MaxEventLimit": "4",                        // Minimum of active freeplay events // TODO(mk) this is not part of the design, only debug
                "DensityLimitMultiplay": "100.0",            // The event density limit for the multiplay game mode
  • In berlin_challenge_eventpools I increase the probability of fires without person damage
            "Building_Fire_NoPerson_Damage":
            {
                "Core": "EM5_StandardEvents/Building_Fire_NoPerson_Damage",    
                "StartEvent": "true",
                "TriggerChance": "2"
            },
            "Building_Fire_Person_At_Window":
            {
                "Core": "EM5_StandardEvents/Building_Fire_Person_At_Window",    // Technical core definition, to be set by programming
                "StartEvent": "true",
                "TriggerChance": "2"
            },

• Activate, play and export the mod
  • To play the mod, make sure that inside the launcher, inside the modifications window, the mod is set active.
  • To hand your skin to other player rightclick your project again > Publish Mod Project.
  • Save a .zip-file.
  • Another player needs only drag this file into the modification window inside the launcher to load the map