diff --git a/source/CCustomOpcodeSystem.cpp b/source/CCustomOpcodeSystem.cpp
index 58ecbe4e..2c544945 100644
--- a/source/CCustomOpcodeSystem.cpp
+++ b/source/CCustomOpcodeSystem.cpp
@@ -25,6 +25,7 @@ namespace CLEO
 
 	OpcodeResult __stdcall opcode_004E(CRunningScript* thread); // terminate_this_script
 	OpcodeResult __stdcall opcode_0051(CRunningScript * thread); // GOSUB return
+	OpcodeResult __stdcall opcode_03D9(CRunningScript* thread); // has_save_game_finished
 	OpcodeResult __stdcall opcode_0417(CRunningScript* thread); // load_and_launch_mission_internal
 
 	OpcodeResult __stdcall opcode_0A92(CRunningScript* thread); // stream_custom_script
@@ -235,6 +236,7 @@ namespace CLEO
 
 		CLEO_RegisterOpcode(0x004E, opcode_004E);
 		CLEO_RegisterOpcode(0x0051, opcode_0051);
+		CLEO_RegisterOpcode(0x03D9, opcode_03D9);
 		CLEO_RegisterOpcode(0x0417, opcode_0417);
 		CLEO_RegisterOpcode(0x0A92, opcode_0A92);
 		CLEO_RegisterOpcode(0x0A93, opcode_0A93);
@@ -823,6 +825,20 @@ namespace CLEO
 		return originalOpcodeHandlers[tableIdx](thread, 0x0051); // call game's original
 	}
 
+	OpcodeResult __stdcall CCustomOpcodeSystem::opcode_03D9(CRunningScript* thread) // has_save_game_finished
+	{
+		if (thread->IsCustom())
+		{
+			bool saveProcessing = (GetInstance().GameState() == GameSessionState::Initial) && (GetInstance().saveSlot) != -1;
+
+			OPCODE_CONDITION_RESULT(!saveProcessing);
+			return OR_CONTINUE;
+		}
+
+		size_t tableIdx = 0x03D9 / 100; // 100 opcodes peer handler table
+		return originalOpcodeHandlers[tableIdx](thread, 0x03D9); // call game's original
+	}
+
 	OpcodeResult __stdcall CCustomOpcodeSystem::opcode_0417(CRunningScript* thread) // load_and_launch_mission_internal
 	{
 		MissionIndex = CLEO_PeekIntOpcodeParam(thread);
diff --git a/source/CCustomOpcodeSystem.h b/source/CCustomOpcodeSystem.h
index 6bd50410..724f8139 100644
--- a/source/CCustomOpcodeSystem.h
+++ b/source/CCustomOpcodeSystem.h
@@ -46,6 +46,7 @@ namespace CLEO
 
         static OpcodeResult __stdcall opcode_004E(CRunningScript* thread); // terminate_this_script
         static OpcodeResult __stdcall opcode_0051(CRunningScript* thread); // GOSUB's return
+        static OpcodeResult __stdcall opcode_03D9(CRunningScript* thread); // has_save_game_finished
         static OpcodeResult __stdcall opcode_0417(CRunningScript* thread); // load_and_launch_mission_internal
 
     private:
diff --git a/source/CleoBase.cpp b/source/CleoBase.cpp
index fefc469a..4b31f5ba 100644
--- a/source/CleoBase.cpp
+++ b/source/CleoBase.cpp
@@ -12,13 +12,13 @@ namespace CLEO
         Stop();
     }
 
-    void __declspec(naked) CCleoInstance::OnUpdateGameLogics()
+    void __cdecl CCleoInstance::OnUpdateGameLogics()
     {
         CleoInstance.CallCallbacks(eCallbackId::GameProcess); // execute registered callbacks
 
-        static DWORD dwFunc;
-        dwFunc = (DWORD)(CleoInstance.UpdateGameLogics);
-        _asm jmp dwFunc
+        CleoInstance.UpdateGameLogics(); // call original function
+
+        CleoInstance.m_gameState = GameSessionState::InProgress;
     }
 
     HWND CCleoInstance::OnCreateMainWnd(HINSTANCE hinst)
@@ -121,7 +121,7 @@ namespace CLEO
     {
         if (stage > InitStage::Done) return; // invalid argument
 
-        auto nextStage = InitStage(m_initStage + 1);
+        auto nextStage = InitStage((size_t)m_initStage + 1);
         if (stage != nextStage) return;
 
         if (stage == InitStage::Initial)
@@ -183,8 +183,8 @@ namespace CLEO
 
     void CCleoInstance::GameBegin()
     {
-        if (m_bGameInProgress) return;
-        m_bGameInProgress = true;
+        if (m_gameState != GameSessionState::None) return;
+        m_gameState = GameSessionState::Initial;
 
         saveSlot = MenuManager->m_bWantToLoad ? MenuManager->m_nSelectedSaveGame : -1;
 
@@ -197,8 +197,8 @@ namespace CLEO
 
     void CCleoInstance::GameEnd()
     {
-        if (!m_bGameInProgress) return;
-        m_bGameInProgress = false;
+        if (m_gameState == GameSessionState::None) return;
+        m_gameState = GameSessionState::None;
 
         TRACE(""); // separator
         TRACE("Ending current game");
diff --git a/source/CleoBase.h b/source/CleoBase.h
index 4423c548..9fe0ac56 100644
--- a/source/CleoBase.h
+++ b/source/CleoBase.h
@@ -15,10 +15,17 @@
 
 namespace CLEO
 {
+    enum class GameSessionState : size_t
+    {
+        None,
+        Initial,
+        InProgress
+    };
+
     class CCleoInstance
     {
     public:
-        enum InitStage : size_t
+        enum class InitStage : size_t
         {
             None,
             Initial,
@@ -47,6 +54,7 @@ namespace CLEO
 
         void GameBegin();
         void GameEnd();
+        GameSessionState GameState() const { return m_gameState; }
 
         bool IsStarted() const { return m_initStage != InitStage::None; }
 
@@ -95,7 +103,7 @@ namespace CLEO
 
     private:
         InitStage m_initStage = InitStage::None;
-        bool m_bGameInProgress;
+        GameSessionState m_gameState = GameSessionState::None;
         std::map<eCallbackId, std::set<void*>> m_callbacks;
     };