diff --git a/src/game-lib/Controller/GameSessionController.cs b/src/game-lib/Controller/GameSessionController.cs
index 5dd17a9b..978938c3 100644
--- a/src/game-lib/Controller/GameSessionController.cs
+++ b/src/game-lib/Controller/GameSessionController.cs
@@ -55,11 +55,14 @@ public GameSessionController(Configuration config, ILog log, GameSession gameSes
             _log,
             GameSession.RandomGen,
             GameSession.EventIdGen,
+            GameSession.AgentIdGen,
+            GameSession.MissionIdGen,
             () => GameSession.CurrentGameState);
         _timeAdvancementController = new TimeAdvancementController(
             _log,
             GameSession.RandomGen,
-            GameSession.EventIdGen);
+            GameSession.EventIdGen,
+            GameSession.MissionSiteIdGen);
     }
 
     public GameStatePlayerView CurrentGameStatePlayerView
diff --git a/src/game-lib/Controller/GameTurnController.cs b/src/game-lib/Controller/GameTurnController.cs
index 4ff7f28d..9dc8f3c7 100644
--- a/src/game-lib/Controller/GameTurnController.cs
+++ b/src/game-lib/Controller/GameTurnController.cs
@@ -9,20 +9,30 @@ namespace UfoGameLib.Controller;
 public class GameTurnController
 {
     private readonly ILog _log;
+    public RandomGen RandomGen { get; }
+    private readonly EventIdGen _eventIdGen;
+    private readonly AgentIdGen _agentIdGen;
+    private readonly MissionIdGen _missionIdGen;
     private readonly Func<GameState> _gameState;
     private GameState GameState => _gameState();
-    private readonly EventIdGen _eventIdGen;
-    private readonly List<PlayerActionEvent> _recordedPlayerActionEvents = new();
-
-    public GameTurnController(ILog log, RandomGen randomGen, EventIdGen eventIdGen, Func<GameState> gameState)
+    private readonly List<PlayerActionEvent> _recordedPlayerActionEvents = [];
+
+    public GameTurnController(
+        ILog log,
+        RandomGen randomGen,
+        EventIdGen eventIdGen,
+        AgentIdGen agentIdGen,
+        MissionIdGen missionIdGen,
+        Func<GameState> gameState)
     {
         _log = log;
         RandomGen = randomGen;
-        _gameState = gameState;
         _eventIdGen = eventIdGen;
+        _agentIdGen = agentIdGen;
+        _missionIdGen = missionIdGen;
+        _gameState = gameState;
     }
 
-    public RandomGen RandomGen { get; }
 
     public int CurrentTurn => GameState.Timeline.CurrentTurn;
 
@@ -60,7 +70,7 @@ public void LaunchMission(MissionSite site, int agentCount)
     }
 
     public PlayerActionEvent HireAgents(int count)
-        => ExecuteAndRecordAction(new HireAgentsPlayerAction(_log, count));
+        => ExecuteAndRecordAction(new HireAgentsPlayerAction(_log, _agentIdGen, count));
 
     public PlayerActionEvent BuyTransportCapacity(int capacity)
         => ExecuteAndRecordAction(new BuyTransportCapacityPlayerAction(_log, capacity));
@@ -81,7 +91,7 @@ public PlayerActionEvent RecallAgents(Agents agents)
         => ExecuteAndRecordAction(new RecallAgentsPlayerAction(_log, agents));
 
     public PlayerActionEvent LaunchMission(MissionSite site, Agents agents)
-        => ExecuteAndRecordAction(new LaunchMissionPlayerAction(_log, site, agents));
+        => ExecuteAndRecordAction(new LaunchMissionPlayerAction(_log, _missionIdGen, site, agents));
 
     public List<PlayerActionEvent> GetAndDeleteRecordedPlayerActionEvents()
     {
diff --git a/src/game-lib/Controller/HireAgentsPlayerAction.cs b/src/game-lib/Controller/HireAgentsPlayerAction.cs
index 674e7e86..41d17760 100644
--- a/src/game-lib/Controller/HireAgentsPlayerAction.cs
+++ b/src/game-lib/Controller/HireAgentsPlayerAction.cs
@@ -1,4 +1,5 @@
 using Lib.Contracts;
+using UfoGameLib.Events;
 using UfoGameLib.Lib;
 using UfoGameLib.Model;
 using UfoGameLib.State;
@@ -8,12 +9,14 @@ namespace UfoGameLib.Controller;
 public class HireAgentsPlayerAction : PlayerAction
 {
     private readonly ILog _log;
+    private readonly AgentIdGen _agentIdGen;
     private readonly int _count;
 
-    public HireAgentsPlayerAction(ILog log, int count)
+    public HireAgentsPlayerAction(ILog log, AgentIdGen agentIdGen, int count)
     {
         Contract.Assert(count >= 1);
         _log = log;
+        _agentIdGen = agentIdGen;
         _count = count;
         
     }
@@ -26,7 +29,7 @@ protected override (List<int>? ids, int? targetId) ApplyImpl(GameState state)
         state.Assets.Money -= totalHireCost;
         for (int i = 0; i < _count; i++)
         {
-            state.Assets.Agents.Add(new Agent(state.NextAgentId, state.Timeline.CurrentTurn));
+            state.Assets.Agents.Add(new Agent(_agentIdGen.Generate, state.Timeline.CurrentTurn));
         }
 
         return (ids: [state.Assets.Agents.Count], targetId: _count);
diff --git a/src/game-lib/Controller/LaunchMissionPlayerAction.cs b/src/game-lib/Controller/LaunchMissionPlayerAction.cs
index 0a01ac1e..fb8ef115 100644
--- a/src/game-lib/Controller/LaunchMissionPlayerAction.cs
+++ b/src/game-lib/Controller/LaunchMissionPlayerAction.cs
@@ -8,14 +8,16 @@ namespace UfoGameLib.Controller;
 public class LaunchMissionPlayerAction : PlayerAction
 {
     private readonly ILog _log;
+    private readonly MissionIdGen _missionIdGen;
     private readonly MissionSite _site;
     private readonly Agents _agents;
 
-    public LaunchMissionPlayerAction(ILog log, MissionSite site, Agents agents)
+    public LaunchMissionPlayerAction(ILog log, MissionIdGen missionIdGen, MissionSite site, Agents agents)
     {
         Contract.Assert(agents.Any());
         agents.AssertCanBeSentOnMission();
         _log = log;
+        _missionIdGen = missionIdGen;
         _site = site;
         _agents = agents;
     }
@@ -33,7 +35,7 @@ protected override (List<int>? ids, int? targetId) ApplyImpl(GameState state)
             $"_agents.Count: {_agents.Count} " +
             $">= _site.RequiredSurvivingAgentsForSuccess: {_site.RequiredSurvivingAgentsForSuccess}");
 
-        int missionId = state.NextMissionId;
+        int missionId = _missionIdGen.Generate;
         var mission = new Mission(missionId, _site, state.Timeline.CurrentTurn, _agents.Count);
 
         Contract.Assert(_agents.All(agent => AgentSurvivalRoll.AgentCanSurvive(agent, mission)));
diff --git a/src/game-lib/Controller/TimeAdvancementController.cs b/src/game-lib/Controller/TimeAdvancementController.cs
index f6b21d41..e32f47e8 100644
--- a/src/game-lib/Controller/TimeAdvancementController.cs
+++ b/src/game-lib/Controller/TimeAdvancementController.cs
@@ -12,12 +12,18 @@ public class TimeAdvancementController
     private readonly RandomGen _randomGen;
     private readonly List<WorldEvent> _worldEvents;
     private readonly EventIdGen _eventIdGen;
+    private readonly MissionSiteIdGen _missionSiteIdGen;
 
-    public TimeAdvancementController(ILog log, RandomGen randomGen, EventIdGen eventIdGen)
+    public TimeAdvancementController(
+        ILog log,
+        RandomGen randomGen,
+        EventIdGen eventIdGen,
+        MissionSiteIdGen missionSiteIdGen)
     {
         _log = log;
         _randomGen = randomGen;
         _eventIdGen = eventIdGen;
+        _missionSiteIdGen = missionSiteIdGen;
         _worldEvents = new List<WorldEvent>();
     }
 
@@ -211,7 +217,7 @@ private int UpdateActiveMissionSites(GameState state)
     }
     private void CreateMissionSites(GameState state)
     {
-        List<MissionSite> missionSites = state.Factions.CreateMissionSites(_log, _randomGen, state);
+        List<MissionSite> missionSites = state.Factions.CreateMissionSites(_log, _randomGen, _missionSiteIdGen, state);
         state.MissionSites.AddRange(missionSites);
     }
 }
\ No newline at end of file
diff --git a/src/game-lib/Events/EventIdGen.cs b/src/game-lib/Events/EventIdGen.cs
index 82b59740..044458a5 100644
--- a/src/game-lib/Events/EventIdGen.cs
+++ b/src/game-lib/Events/EventIdGen.cs
@@ -1,14 +1,14 @@
 using Lib.Contracts;
+using UfoGameLib.Lib;
 using UfoGameLib.State;
 
 namespace UfoGameLib.Events;
 
-public class EventIdGen
+public class EventIdGen : IdGen
 {
-    private int _nextEventId;
-
     public EventIdGen(List<GameSessionTurn> turns)
     {
+        Contract.Assert(turns.Any());
         // To compute starting next event ID we first need to determine if there are any events in the input
         // game session turns. If yes, we consider as the starting next event ID to be (last event ID + 1).
         // If not, we consider the last turn NextEventId value, if set.
@@ -28,10 +28,6 @@ public EventIdGen(List<GameSessionTurn> turns)
             nextEventIdFromLastEvent is null || nextEventIdFromLastTurn is null ||
             nextEventIdFromLastEvent == nextEventIdFromLastTurn,
             $"nextEventIdFromLastEvent: {nextEventIdFromLastEvent}, nextEventIdFromLastTurn: {nextEventIdFromLastTurn}");
-        _nextEventId = nextEventIdFromLastEvent ?? nextEventIdFromLastTurn ?? 0;
+        NextId = nextEventIdFromLastEvent ?? nextEventIdFromLastTurn ?? 0;
     }
-    
-    public int Generate => _nextEventId++;
-
-    public int Value => _nextEventId;
 }
\ No newline at end of file
diff --git a/src/game-lib/Lib/IdGen.cs b/src/game-lib/Lib/IdGen.cs
new file mode 100644
index 00000000..15bd9b1e
--- /dev/null
+++ b/src/game-lib/Lib/IdGen.cs
@@ -0,0 +1,10 @@
+namespace UfoGameLib.Lib;
+
+public class IdGen
+{
+    protected int NextId;
+
+    public int Generate => NextId++;
+
+    public int Value => NextId;
+}
\ No newline at end of file
diff --git a/src/game-lib/Model/AgentIdGen.cs b/src/game-lib/Model/AgentIdGen.cs
new file mode 100644
index 00000000..59e12a76
--- /dev/null
+++ b/src/game-lib/Model/AgentIdGen.cs
@@ -0,0 +1,12 @@
+using UfoGameLib.Lib;
+using UfoGameLib.State;
+
+namespace UfoGameLib.Model;
+
+public class AgentIdGen : IdGen
+{
+    public AgentIdGen(List<GameSessionTurn> turns)
+    {
+        NextId = turns.Last().EndState.AllAgents.Count;
+    }
+}
diff --git a/src/game-lib/Model/Faction.cs b/src/game-lib/Model/Faction.cs
index 95fc75e3..c76cd632 100644
--- a/src/game-lib/Model/Faction.cs
+++ b/src/game-lib/Model/Faction.cs
@@ -55,7 +55,11 @@ public static Faction Init(
     public Faction DeepClone()
         => new(Id, Name, Power, MissionSiteCountdown, PowerIncrease, PowerAcceleration, IntelInvested);
 
-    public List<MissionSite> CreateMissionSites(ILog log, RandomGen randomGen, GameState state)
+    public List<MissionSite> CreateMissionSites(
+        ILog log,
+        RandomGen randomGen,
+        MissionSiteIdGen missionSiteIdGen,
+        GameState state)
     {
         Contract.Assert(MissionSiteCountdown >= 1);
 
@@ -69,8 +73,7 @@ public List<MissionSite> CreateMissionSites(ILog log, RandomGen randomGen, GameS
         // kja2-simul-feat to make simulation more interesting: create easier missions from time to time and
         // make AI player send less experienced soldiers on it.
         List<MissionSite> sites = [];
-        // kja BUG ROOT CAUSE: this must increase the ID, right now it does not.
-        int siteId = state.NextMissionSiteId;
+        int siteId = missionSiteIdGen.Generate;
         (int difficulty, int difficultyFromTurn, int roll) =
             Ruleset.RollMissionSiteDifficulty(state.Timeline.CurrentTurn, randomGen);
 
diff --git a/src/game-lib/Model/Factions.cs b/src/game-lib/Model/Factions.cs
index 54391ff5..d1900c8b 100644
--- a/src/game-lib/Model/Factions.cs
+++ b/src/game-lib/Model/Factions.cs
@@ -17,6 +17,10 @@ public Factions(IEnumerable<Faction>? factions = null)
     public Factions DeepClone()
         => new Factions(this.Select(faction => faction.DeepClone()));
 
-    public List<MissionSite> CreateMissionSites(ILog log, RandomGen randomGen, GameState state)
-        => this.SelectMany(faction => faction.CreateMissionSites(log, randomGen, state)).ToList();
+    public List<MissionSite> CreateMissionSites(
+        ILog log,
+        RandomGen randomGen,
+        MissionSiteIdGen missionSiteIdGen,
+        GameState state)
+        => this.SelectMany(faction => faction.CreateMissionSites(log, randomGen, missionSiteIdGen, state)).ToList();
 }
\ No newline at end of file
diff --git a/src/game-lib/Model/MissionIdGen.cs b/src/game-lib/Model/MissionIdGen.cs
new file mode 100644
index 00000000..f85e043f
--- /dev/null
+++ b/src/game-lib/Model/MissionIdGen.cs
@@ -0,0 +1,14 @@
+using Lib.Contracts;
+using UfoGameLib.Lib;
+using UfoGameLib.State;
+
+namespace UfoGameLib.Model;
+
+public class MissionIdGen : IdGen
+{
+    public MissionIdGen(List<GameSessionTurn> turns)
+    {
+        Contract.Assert(turns.Any());
+        NextId = turns.Last().EndState.Missions.Count;
+    }
+}
\ No newline at end of file
diff --git a/src/game-lib/Model/MissionSiteIdGen.cs b/src/game-lib/Model/MissionSiteIdGen.cs
new file mode 100644
index 00000000..56ff6d39
--- /dev/null
+++ b/src/game-lib/Model/MissionSiteIdGen.cs
@@ -0,0 +1,14 @@
+using Lib.Contracts;
+using UfoGameLib.Lib;
+using UfoGameLib.State;
+
+namespace UfoGameLib.Model;
+
+public class MissionSiteIdGen : IdGen
+{
+    public MissionSiteIdGen(List<GameSessionTurn> turns)
+    {
+        Contract.Assert(turns.Any());
+        NextId = turns.Last().EndState.MissionSites.Count;
+    }
+}
\ No newline at end of file
diff --git a/src/game-lib/Model/Ruleset.cs b/src/game-lib/Model/Ruleset.cs
index 5e792b2e..ac70ae96 100644
--- a/src/game-lib/Model/Ruleset.cs
+++ b/src/game-lib/Model/Ruleset.cs
@@ -3,7 +3,7 @@
 
 namespace UfoGameLib.Model;
 
-// kja convert "Ruleset" class into a namespace. Maybe introduce IRuleset "marker" interface?
+// kja2-refactor convert "Ruleset" class into a namespace. Maybe introduce IRuleset "marker" interface?
 public static class Ruleset
 {
     public const int InitialMoney = 500;
diff --git a/src/game-lib/State/GameSession.cs b/src/game-lib/State/GameSession.cs
index 1606877a..a1eb7769 100644
--- a/src/game-lib/State/GameSession.cs
+++ b/src/game-lib/State/GameSession.cs
@@ -1,6 +1,7 @@
 using Lib.Contracts;
 using UfoGameLib.Events;
 using UfoGameLib.Lib;
+using UfoGameLib.Model;
 
 namespace UfoGameLib.State;
 
@@ -27,22 +28,28 @@ public class GameSession
 
     public readonly EventIdGen EventIdGen;
 
+    public readonly AgentIdGen AgentIdGen;
+
+    public readonly MissionIdGen MissionIdGen;
+
+    public readonly MissionSiteIdGen MissionSiteIdGen;
+
     public GameSession(RandomGen randomGen, List<GameSessionTurn>? turns = null)
     {
         RandomGen = randomGen;
         Turns = turns ?? [new GameSessionTurn(startState: GameState.NewInitialGameState(randomGen))];
-        Contract.Assert(Turns.Count >= 1);
+        Contract.Assert(Turns.Any());
         Turns.ForEach(turn => turn.AssertInvariants());
+        
         EventIdGen = new EventIdGen(Turns);
+        AgentIdGen = new AgentIdGen(Turns);
+        MissionSiteIdGen = new MissionSiteIdGen(Turns);
+        MissionIdGen = new MissionIdGen(Turns);
+        
     }
 
     public IReadOnlyList<GameState> GameStates
         => Turns.SelectMany<GameSessionTurn, GameState>(turn => [turn.StartState, turn.EndState])
             .ToList()
             .AsReadOnly();
-
-    public IReadOnlyList<GameEvent> GameEvents
-        => Turns.SelectMany<GameSessionTurn, GameEvent>(turn => turn.GameEvents)
-            .ToList()
-            .AsReadOnly();
 }
\ No newline at end of file
diff --git a/src/game-lib/State/GameState.cs b/src/game-lib/State/GameState.cs
index e4ef2b7e..159d7cd3 100644
--- a/src/game-lib/State/GameState.cs
+++ b/src/game-lib/State/GameState.cs
@@ -76,10 +76,6 @@ public void ToJsonFile(File file)
 
     public bool IsGameWon => Assets.Intel >= Ruleset.IntelToWin;
 
-    public int NextAgentId => AllAgents.Count;
-    public int NextMissionId => Missions.Count;
-    public int NextMissionSiteId => MissionSites.Count;
-
     public void Terminate(Agent agent, bool sack = false)
     {
         Assets.Agents.Remove(agent);