Submarine is invisible now, except to submarines and destroyers. But it still can be aimed by everybody.

android/assets/jsons/Units.json

@@ -467,7 +467,7 @@
 		strength:55,
 		cost: 375,
 		requiredTech:"Combustion",
-		uniques:[], // todo: add interception and bonus vs submarines once we have air and submarine units
+		uniques:["Can attack submarines"], // todo: add interception and bonus vs submarines once we have air and submarine units
 		hurryCostModifier:20
 	},
 	{
@@ -491,7 +491,7 @@
 		rangedStrength: 60,
 		cost: 325,
 		requiredTech:"Refrigeration",
-		uniques:["Bonus as Attacker 75%", "Invisible to others", "Can Only Attack Water"], //to do: 3 uniques
+		uniques:["Bonus as Attacker 75%", "Invisible to others", "Can Only Attack Water", "Can attack submarines"], //to do: 3 uniques
 		hurryCostModifier:20
 	},
 	{

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

@@ -33,6 +33,7 @@ class CivilizationInfo {
      */
     @Transient private var units=ArrayList<MapUnit>()
     @Transient var viewableTiles = HashSet<TileInfo>()
+    @Transient var viewableInvisibleUnitsTiles = HashSet<TileInfo>()
 
     var gold = 0
     var happiness = 15
@@ -228,6 +229,9 @@ class CivilizationInfo {
         newViewableTiles.addAll(getCivUnits().flatMap { it.getViewableTiles()})
         viewableTiles = newViewableTiles // to avoid concurrent modification problems
 
+        val newViewableInvisibleTiles = HashSet<TileInfo>()
+        newViewableInvisibleTiles.addAll(getCivUnits().filter {it.hasUnique("Can attack submarines")}.flatMap {it.getViewableTiles()})
+        viewableInvisibleUnitsTiles = newViewableInvisibleTiles
         // updating the viewable tiles also affects the explored tiles, obvs
 
         val newExploredTiles = HashSet<Vector2>(exploredTiles)

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

@@ -177,6 +177,12 @@ class MapUnit {
         return currentTile.baseTerrain=="Ocean"||currentTile.baseTerrain=="Coast"
     }
 
+    fun isInvisible(): Boolean {
+        if(hasUnique("Invisible to others"))
+            return true
+        return false
+    }
+
     fun getEmbarkedMovement(): Int {
         var movement=2
         movement += civInfo.tech.getUniques().count { it == "Increases embarked movement +1" }

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

@@ -281,5 +281,14 @@ open class TileInfo {
         turnsToImprovement = improvement.getTurnsToBuild(civInfo)
     }
 
+    fun hasEnemySubmarine(): Boolean {
+        val unitsInTile = getUnits()
+        if (unitsInTile.isEmpty()) return false
+        if (!unitsInTile.first().civInfo.isPlayerCivilization() &&
+                unitsInTile.firstOrNull {it.isInvisible() == true} != null) {
+            return true
+        }
+        return false
+    }
     //endregion
 }

core/src/com/unciv/ui/cityscreen/CityTileGroup.kt

@@ -23,8 +23,10 @@ class CityTileGroup(private val city: CityInfo, tileInfo: TileInfo) : TileGroup(
     fun update() {
         val canSeeTile = UnCivGame.Current.viewEntireMapForDebug
                 || city.civInfo.viewableTiles.contains(tileInfo)
-
+        val showSubmarine = UnCivGame.Current.viewEntireMapForDebug
-        super.update(canSeeTile,true)
+                || city.civInfo.viewableInvisibleUnitsTiles.contains(tileInfo)
+                || (!tileInfo.hasEnemySubmarine())
+        super.update(canSeeTile,true, showSubmarine)
 
         updatePopulationImage()
         if (improvementImage != null) improvementImage!!.setColor(1f, 1f, 1f, 0.5f)

core/src/com/unciv/ui/tilegroups/TileGroup.kt

@@ -133,7 +133,7 @@ open class TileGroup(var tileInfo: TileInfo) : Group() {
     }
 
 
-    open fun update(isViewable: Boolean, showResourcesAndImprovements:Boolean) {
+    open fun update(isViewable: Boolean, showResourcesAndImprovements:Boolean, showSubmarine: Boolean) {
         hideCircle()
         if (!UnCivGame.Current.viewEntireMapForDebug
                 && !tileInfo.tileMap.gameInfo.getPlayerCivilization().exploredTiles.contains(tileInfo.position)) {
@@ -150,7 +150,7 @@ open class TileGroup(var tileInfo: TileInfo) : Group() {
 
 
         civilianUnitImage = newUnitImage(tileInfo.civilianUnit, civilianUnitImage, isViewable, -20f)
-        militaryUnitImage = newUnitImage(tileInfo.militaryUnit, militaryUnitImage, isViewable, 20f)
+        militaryUnitImage = newUnitImage(tileInfo.militaryUnit, militaryUnitImage, isViewable && showSubmarine, 20f)
 
         updateRoadImages()
         updateBorderImages()

core/src/com/unciv/ui/tilegroups/WorldTileGroup.kt

@@ -23,7 +23,7 @@ class WorldTileGroup(tileInfo: TileInfo) : TileGroup(tileInfo) {
     }
 
 
-    fun update(isViewable: Boolean) {
+    fun update(isViewable: Boolean, showSubmarine: Boolean) {
         val city = tileInfo.getCity()
 
         removePopulationIcon()
@@ -36,7 +36,7 @@ class WorldTileGroup(tileInfo: TileInfo) : TileGroup(tileInfo) {
             updateCityButton(city, isViewable || UnCivGame.Current.viewEntireMapForDebug) // needs to be before the update so the units will be above the city button
 
         super.update(isViewable || UnCivGame.Current.viewEntireMapForDebug,
-                UnCivGame.Current.settings.showResourcesAndImprovements)
+                UnCivGame.Current.settings.showResourcesAndImprovements, showSubmarine)
 
         yieldGroup.isVisible = !UnCivGame.Current.settings.showResourcesAndImprovements
         if (yieldGroup.isVisible)

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

@@ -180,6 +180,7 @@ class TileMapHolder(internal val worldScreen: WorldScreen, internal val tileMap:
 
     internal fun updateTiles(civInfo: CivilizationInfo) {
         val playerViewableTilePositions = civInfo.viewableTiles.map { it.position }.toHashSet()
+        val playerViewableInvisibleUnitsTilePositions = civInfo.viewableInvisibleUnitsTiles.map { it.position }.toHashSet()
 
         cityButtonOverlays.forEach{it.remove()}
         cityButtonOverlays.clear()
@@ -187,9 +188,16 @@ class TileMapHolder(internal val worldScreen: WorldScreen, internal val tileMap:
         for (tileGroup in tileGroups.values){
             val canSeeTile = UnCivGame.Current.viewEntireMapForDebug
                     || playerViewableTilePositions.contains(tileGroup.tileInfo.position)
-            tileGroup.update(canSeeTile)
+
+            val showSubmarine = UnCivGame.Current.viewEntireMapForDebug
+                    || playerViewableInvisibleUnitsTilePositions.contains(tileGroup.tileInfo.position)
+                    || (!tileGroup.tileInfo.hasEnemySubmarine())
+            tileGroup.update(canSeeTile, showSubmarine)
+
             val unitsInTile = tileGroup.tileInfo.getUnits()
-            if(canSeeTile && unitsInTile.isNotEmpty() && !unitsInTile.first().civInfo.isPlayerCivilization())
+            val canSeeEnemy = unitsInTile.isNotEmpty() && !unitsInTile.first().civInfo.isPlayerCivilization()
+                    && (showSubmarine || unitsInTile.firstOrNull {!it.isInvisible()}!=null)
+            if(canSeeTile && canSeeEnemy)
                 tileGroup.showCircle(Color.RED) // Display ALL viewable enemies with a red circle so that users don't need to go "hunting" for enemy units
         }