diff --git a/src/OpenSHC/Synchrony/Commands/CommandCheckSync.cpp b/src/OpenSHC/Synchrony/Commands/CommandCheckSync.cpp
new file mode 100644
index 00000000..3bd38011
--- /dev/null
+++ b/src/OpenSHC/Synchrony/Commands/CommandCheckSync.cpp
@@ -0,0 +1,64 @@
+#include "../Commands.func.hpp"
+
+#include "OpenSHC/Synchrony/GameSynchronyState.func.hpp"
+
+#include "OpenSHC/Globals/DAT_GameSynchronyState.hpp"
+
+namespace OpenSHC {
+namespace Synchrony {
+    namespace Commands {
+
+        // FUNCTION: STRONGHOLDCRUSADER 0x00480B10
+        void __cdecl CommandCheckSync()
+        {
+            DAT_GameSynchronyState::instance.DAT_CommandSize = 10;
+            DAT_GameSynchronyState::instance
+                .DAT_GameCommandArray[DAT_GameSynchronyState::instance.DAT_CurrentGameCommandID]
+                .time = 0;
+
+            // Immediate synchronization traffic uses the fixed parameter buffer.
+            // Scheduling a received command only declares its size and timestamp.
+            if (DAT_GameSynchronyState::instance.DAT_CommandActionPlan == OpenSHC::Commands::GCS_SCHEDULE_AND_SEND) {
+                MACRO_CALL_MEMBER(
+                    GameSynchronyState_Func::serializeOrDeserializeCommandParameter, DAT_GameSynchronyState::ptr)(
+                    &DAT_GameSynchronyState::instance
+                        .DAT_LagIndicatorPerPlayer[DAT_GameSynchronyState::instance.currentPlayerSlotID],
+                    2, OpenSHC::Commands::GCPL_FIXED_COMMAND_DATA_ADDRESS,
+                    OpenSHC::Commands::GCPRW_SERIALIZE_INTO_PARAM_1);
+                MACRO_CALL_MEMBER(
+                    GameSynchronyState_Func::serializeOrDeserializeCommandParameter, DAT_GameSynchronyState::ptr)(
+                    &DAT_GameSynchronyState::instance
+                        .HASH_HashTotal[DAT_GameSynchronyState::instance.currentPlayerSlotID],
+                    4, OpenSHC::Commands::GCPL_FIXED_COMMAND_DATA_ADDRESS,
+                    OpenSHC::Commands::GCPRW_SERIALIZE_INTO_PARAM_1);
+                MACRO_CALL_MEMBER(
+                    GameSynchronyState_Func::serializeOrDeserializeCommandParameter, DAT_GameSynchronyState::ptr)(
+                    &DAT_GameSynchronyState::instance
+                        .DAT_PlayerMatchTimes[DAT_GameSynchronyState::instance.currentPlayerSlotID],
+                    4, OpenSHC::Commands::GCPL_FIXED_COMMAND_DATA_ADDRESS,
+                    OpenSHC::Commands::GCPRW_SERIALIZE_INTO_PARAM_1);
+            } else if (DAT_GameSynchronyState::instance.DAT_CommandActionPlan == OpenSHC::Commands::GCS_EXECUTE) {
+                MACRO_CALL_MEMBER(
+                    GameSynchronyState_Func::serializeOrDeserializeCommandParameter, DAT_GameSynchronyState::ptr)(
+                    &DAT_GameSynchronyState::instance
+                        .DAT_LagIndicatorPerPlayer[DAT_GameSynchronyState::instance.protocolInvokerPlayerID],
+                    2, OpenSHC::Commands::GCPL_FIXED_COMMAND_DATA_ADDRESS,
+                    OpenSHC::Commands::GCPRW_DESERIALIZE_FROM_PARAM1);
+                MACRO_CALL_MEMBER(
+                    GameSynchronyState_Func::serializeOrDeserializeCommandParameter, DAT_GameSynchronyState::ptr)(
+                    &DAT_GameSynchronyState::instance
+                        .HASH_HashTotal[DAT_GameSynchronyState::instance.protocolInvokerPlayerID],
+                    4, OpenSHC::Commands::GCPL_FIXED_COMMAND_DATA_ADDRESS,
+                    OpenSHC::Commands::GCPRW_DESERIALIZE_FROM_PARAM1);
+                MACRO_CALL_MEMBER(
+                    GameSynchronyState_Func::serializeOrDeserializeCommandParameter, DAT_GameSynchronyState::ptr)(
+                    &DAT_GameSynchronyState::instance
+                        .DAT_PlayerMatchTimes[DAT_GameSynchronyState::instance.protocolInvokerPlayerID],
+                    4, OpenSHC::Commands::GCPL_FIXED_COMMAND_DATA_ADDRESS,
+                    OpenSHC::Commands::GCPRW_DESERIALIZE_FROM_PARAM1);
+            }
+        }
+
+    } // namespace Commands
+} // namespace Synchrony
+} // namespace OpenSHC