We can now support mods with no techs whatsoever!

core/src/com/unciv/logic/battle/CityCombatant.kt

@@ -40,10 +40,11 @@ class CityCombatant(val city: CityInfo) : ICombatant {
         val cityTile = city.getCenterTile()
         if(cityTile.baseTerrain== Constants.hill) strength+=5
         // as tech progresses so does city strength
-        val techsPercentKnown: Float = city.civInfo.tech.techsResearched.count().toFloat() /
-                getCivInfo().gameInfo.ruleSet.technologies.count()
+        val techCount = getCivInfo().gameInfo.ruleSet.technologies.count()
+        val techsPercentKnown: Float = if(techCount>0) city.civInfo.tech.techsResearched.count().toFloat() / techCount else 0.5f // for mods with no tech
         strength += (techsPercentKnown * 5.5).pow(2.8).toFloat()
 
+
         // The way all of this adds up...
         // All ancient techs - 0.5 extra, Classical - 2.7, Medieval - 8, Renaissance - 17.5,
         // Industrial - 32.4, Modern - 51, Atomic - 72.5, All - 118.3

core/src/com/unciv/logic/city/CityInfo.kt

@@ -541,13 +541,17 @@ class CityInfo {
     }
 
     private fun tryUpdateRoadStatus(){
-        if(getCenterTile().roadStatus==RoadStatus.None
-                && getRuleset().tileImprovements["Road"]!!.techRequired in civInfo.tech.techsResearched)
+        if(getCenterTile().roadStatus==RoadStatus.None){
+            val roadImprovement = getRuleset().tileImprovements["Road"]
+            if(roadImprovement!=null && roadImprovement.techRequired in civInfo.tech.techsResearched)
             getCenterTile().roadStatus=RoadStatus.Road
+        }
 
-        else if(getCenterTile().roadStatus!=RoadStatus.Railroad
-                && getRuleset().tileImprovements["Railroad"]!!.techRequired in civInfo.tech.techsResearched)
-            getCenterTile().roadStatus=RoadStatus.Railroad
+        else if (getCenterTile().roadStatus != RoadStatus.Railroad) {
+            val railroadImprovement = getRuleset().tileImprovements["Railroad"]
+            if (railroadImprovement != null && railroadImprovement.techRequired in civInfo.tech.techsResearched)
+                getCenterTile().roadStatus = RoadStatus.Railroad
+        }
     }
 
     fun getGoldForSellingBuilding(buildingName:String) = getRuleset().buildings[buildingName]!!.cost / 10

core/src/com/unciv/logic/city/CityStats.kt

@@ -73,7 +73,9 @@ class CityStats {
 
     private fun getStatPercentBonusesFromRailroad(): Stats {
         val stats = Stats()
-        val techEnablingRailroad = cityInfo.getRuleset().tileImprovements["Railroad"]!!.techRequired!!
+        val railroadImprovement = cityInfo.getRuleset().tileImprovements["Railroad"]
+        if (railroadImprovement == null) return stats // for mods
+        val techEnablingRailroad = railroadImprovement.techRequired!!
         // If we conquered enemy cities connected by railroad, but we don't yet have that tech,
         // we shouldn't get bonuses, it's as if the tracks aare layed out but we can't operate them.
         if (cityInfo.civInfo.tech.isResearched(techEnablingRailroad)

core/src/com/unciv/logic/civilization/CivilizationInfo.kt

@@ -220,8 +220,11 @@ class CivilizationInfo {
     }
     //endregion
 
-    fun shouldOpenTechPicker() = tech.freeTechs != 0
-            || tech.currentTechnology()==null && cities.isNotEmpty()
+    fun shouldOpenTechPicker(): Boolean {
+        if (gameInfo.ruleSet.technologies.isEmpty()) return false
+        if (tech.freeTechs != 0) return true
+        return tech.currentTechnology() == null && cities.isNotEmpty()
+    }
 
 
 
@@ -435,7 +438,8 @@ class CivilizationInfo {
 
         gold += nextTurnStats.gold.toInt()
 
-        if (cities.isNotEmpty()) tech.nextTurn(nextTurnStats.science.toInt())
+        if (cities.isNotEmpty() && gameInfo.ruleSet.technologies.isNotEmpty())
+            tech.nextTurn(nextTurnStats.science.toInt())
 
         if (isMajorCiv()) greatPeople.addGreatPersonPoints(getGreatPersonPointsForNextTurn()) // City-states don't get great people!
 

core/src/com/unciv/logic/map/MapUnit.kt

@@ -580,7 +580,8 @@ class MapUnit {
             }
 
         actions.add {
-            val chosenUnit = listOf(Constants.settler, Constants.worker,"Warrior").random(tileBasedRandom)
+            val chosenUnit = listOf(Constants.settler, Constants.worker,"Warrior")
+                    .filter { civInfo.gameInfo.ruleSet.units.containsKey(it) }.random(tileBasedRandom)
             if (!(civInfo.isCityState() || civInfo.isOneCityChallenger()) || chosenUnit != Constants.settler) { //City states and OCC don't get settler from ruins
                 civInfo.placeUnitNearTile(tile.position, chosenUnit)
                 civInfo.addNotification("A [$chosenUnit] has joined us!", tile.position, Color.BROWN)

core/src/com/unciv/ui/worldscreen/Minimap.kt

@@ -135,7 +135,7 @@ class MinimapHolder(mapHolder: WorldMapHolder): Table(){
         }
         toggleIconTable.add(populationImage).row()
 
-        val resourceImage = ImageGetter.getResourceImage("Cattle",30f).surroundWithCircle(40f)
+        val resourceImage = ImageGetter.getImage("ResourceImages/Cattle").surroundWithCircle(40f)
         resourceImage.circle.color = Color.BLACK
         resourceImage.actor.color.a = if(settings.showResourcesAndImprovements) 1f else 0.5f
         resourceImage.onClick {

core/src/com/unciv/ui/worldscreen/WorldScreen.kt

@@ -386,6 +386,7 @@ class WorldScreen(val viewingCiv:CivilizationInfo) : CameraStageBaseScreen() {
     }
 
     private fun updateTechButton() {
+        if(gameInfo.ruleSet.technologies.isEmpty()) return
         techButtonHolder.isVisible = viewingCiv.cities.isNotEmpty()
         techButtonHolder.clearChildren()