diff --git a/src/event/Event.cpp b/src/event/Event.cpp
index 6d25f25..a8573a6 100644
--- a/src/event/Event.cpp
+++ b/src/event/Event.cpp
@@ -53,7 +53,28 @@ int32_t EventIsControlKeyDown() {
 }
 
 int32_t EventIsKeyDown(KEY key) {
-    // TODO
+    auto hContext = PropGet(PROP_EVENTCONTEXT);
+    auto contextId = *reinterpret_cast<uint32_t*>(hContext);
+    int32_t findMask;
+
+    auto context = TSingletonInstanceId<EvtContext, offsetof(EvtContext, m_id)>::s_idTable.Ptr(
+        contextId,
+        0,
+        &findMask
+    );
+
+    if (context) {
+        auto keystate = IEvtQueueCheckSyncKeyState(context, key);
+
+        if (findMask != -1) {
+            TSingletonInstanceId<EvtContext, offsetof(EvtContext, m_id)>::s_idTable.Unlock(
+                findMask & (INSTANCE_TABLE_SLOT_COUNT - 1),
+                findMask >= INSTANCE_TABLE_SLOT_COUNT
+            );
+        }
+
+        return keystate;
+    }
     return 0;
 }
 
diff --git a/src/event/Queue.cpp b/src/event/Queue.cpp
index 47734fb..03bb4db 100644
--- a/src/event/Queue.cpp
+++ b/src/event/Queue.cpp
@@ -3,11 +3,89 @@
 #include "event/EvtHandler.hpp"
 #include <storm/Error.hpp>
 
+void UpdateSyncMouseState(EvtContext* context, MOUSEBUTTON button, int32_t down) {
+    if (down) {
+        context->m_queueSyncButtonState |= button;
+    } else {
+        context->m_queueSyncButtonState &= ~button;
+    }
+}
+
+void UpdateSyncKeyState(EvtContext* context, KEY key, EVENTID& id) {
+    context->m_critsect.Enter();
+
+    int32_t keyDown = 0;
+
+    auto list = &context->m_queueSyncKeyDownList;
+
+    for (auto node = list->Head(); node;) {
+        if (node->key == key) {
+            keyDown = 1;
+            auto dead = node;
+            node = list->Next(node);
+            list->UnlinkNode(dead);
+            list->DeleteNode(dead);
+        } else {
+            node = list->Next(node);
+        }
+    }
+
+    if (id == EVENT_ID_KEYDOWN) {
+        if (keyDown) {
+            id = EVENT_ID_KEYDOWN_REPEATING;
+        }
+
+        auto node = context->m_queueSyncKeyDownList.NewNode(2, 0, 0);
+        node->key = key;
+    }
+
+    context->m_critsect.Leave();
+}
+
+void ResetSyncState(EvtContext* context) {
+    context->m_queueSyncButtonState = 0;
+
+    context->m_critsect.Enter();
+
+    EvtKeyDown* node;
+
+    auto list = &context->m_queueSyncKeyDownList;
+
+    while (node = list->Head()) {
+        list->UnlinkNode(node);
+        list->DeleteNode(node);
+    }
+
+    context->m_critsect.Leave();
+}
+
+void UpdateSyncState(EvtContext* context, EVENTID& id, const void* data) {
+    KEY key;
+    MOUSEBUTTON button;
+
+    STORM_ASSERT(context);
+
+    switch (id) {
+    case EVENT_ID_FOCUS:
+        ResetSyncState(context);
+        break;
+    case EVENT_ID_KEYDOWN:
+    case EVENT_ID_KEYUP:
+        key = reinterpret_cast<const EVENT_DATA_KEY*>(data)->key;
+        UpdateSyncKeyState(context, key, id);
+        break;
+    case EVENT_ID_MOUSEDOWN:
+    case EVENT_ID_MOUSEUP:
+        button = reinterpret_cast<const EVENT_DATA_MOUSE*>(data)->button;
+        UpdateSyncMouseState(context, button, id == EVENT_ID_MOUSEDOWN);
+        break;
+    }
+}
+
 void IEvtQueueDispatch(EvtContext* context, EVENTID id, const void* data) {
     STORM_ASSERT(context);
 
-    // TODO
-    // UpdateSyncState(data, &id, context, v3);
+    UpdateSyncState(context, id, data);
 
     // TODO
     // if (SErrIsDisplayingError()) {
@@ -65,3 +143,24 @@ void IEvtQueueRegister(EvtContext* context, EVENTID id, int32_t (*handler)(const
 
     handlerList->LinkNode(evtHandler, 2, h);
 }
+
+int32_t IEvtQueueCheckSyncKeyState(EvtContext* context, KEY key) {
+    STORM_VALIDATE(context, ERROR_INVALID_PARAMETER, 0);
+
+    context->m_critsect.Enter();
+
+    int32_t keystate = 0;
+
+    auto list = &context->m_queueSyncKeyDownList;
+
+    for (auto node = list->Head(); node; node = list->Next(node)) {
+        if (node->key == key) {
+            keystate = 1;
+            break;
+        }
+    }
+
+    context->m_critsect.Leave();
+
+    return keystate;
+}
diff --git a/src/event/Queue.hpp b/src/event/Queue.hpp
index f916f0c..642e9f7 100644
--- a/src/event/Queue.hpp
+++ b/src/event/Queue.hpp
@@ -11,4 +11,6 @@ void IEvtQueueDispatchAll(EvtContext* context);
 
 void IEvtQueueRegister(EvtContext* context, EVENTID id, int32_t (*handler)(const void*, void*), void* param, float priority);
 
+int32_t IEvtQueueCheckSyncKeyState(EvtContext* context, KEY key);
+
 #endif