diff --git a/assets/css/mineseeker/_waiting-dialog.scss b/assets/css/mineseeker/_waiting-dialog.scss
index 8b9983b..3f6d868 100644
--- a/assets/css/mineseeker/_waiting-dialog.scss
+++ b/assets/css/mineseeker/_waiting-dialog.scss
@@ -305,3 +305,43 @@
   padding-top: 14px;
   border-top: 1px solid rgba(35, 111, 135, 0.14);
 }
+
+.opd-header-actions {
+  .opd-refresh[disabled] {
+    opacity: 0.4;
+    cursor: not-allowed;
+  }
+
+  .opd-close[disabled] {
+    opacity: 0.4;
+    cursor: not-allowed;
+  }
+}
+
+.opd-waiting {
+  display: flex;
+  align-items: center;
+  gap: 10px;
+  padding: 14px 16px;
+  margin-bottom: 16px;
+  background: rgba(35, 111, 135, 0.07);
+  border: 1px solid rgba(35, 111, 135, 0.28);
+  border-radius: 8px;
+  color: #95cff5;
+
+  i {
+    font-size: 16px;
+    animation: opd-hourglass 1s ease-in-out infinite;
+  }
+
+  p {
+    margin: 0;
+    font: 600 14px 'Rajdhani', sans-serif;
+    letter-spacing: 0.5px;
+  }
+}
+
+@keyframes opd-hourglass {
+  0%, 100% { transform: rotate(0deg); }
+  50% { transform: rotate(180deg); }
+}
diff --git a/assets/js/mine-seeker/components/ChallengeCountdown.jsx b/assets/js/mine-seeker/components/ChallengeCountdown.jsx
new file mode 100644
index 0000000..6719d98
--- /dev/null
+++ b/assets/js/mine-seeker/components/ChallengeCountdown.jsx
@@ -0,0 +1,41 @@
+/**
+ * This file is part of the SplendidBear Websites' projects.
+ *
+ * Copyright (c) 2026 @ www.splendidbear.org
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+import { Fragment, useEffect, useState } from 'react';
+
+const ChallengeCountdown = ({ onAccept, onDecline, seconds = 30 }) => {
+  const [countdown, setCountdown] = useState(seconds);
+
+  useEffect(() => {
+    const interval = setInterval(() => {
+      setCountdown(prev => {
+        if (1 >= prev) {
+          clearInterval(interval);
+          onDecline();
+          return 0;
+        }
+        return prev - 1;
+      });
+    }, 1000);
+    return () => clearInterval(interval);
+  }, [onDecline]);
+
+  return (
+    <Fragment>
+      <p style={{ textAlign: 'center', marginBottom: 20, color: '#95cff5' }}>
+        You have {countdown} second{1 === countdown ? '' : 's'} to answer to the challenge!
+      </p>
+      <div className="resign">
+        <a onClick={onAccept}>Accept</a>
+        <a onClick={onDecline}>Decline</a>
+      </div>
+    </Fragment>
+  );
+};
+
+export default ChallengeCountdown;
diff --git a/assets/js/mine-seeker/components/OnlinePlayersDialog.jsx b/assets/js/mine-seeker/components/OnlinePlayersDialog.jsx
index ee1bb4c..a135142 100644
--- a/assets/js/mine-seeker/components/OnlinePlayersDialog.jsx
+++ b/assets/js/mine-seeker/components/OnlinePlayersDialog.jsx
@@ -47,6 +47,7 @@ const OnlinePlayersDialog = ({ open, onClose, currentGameAssoc }) => {
   const [snapshotLoaded, setSnapshotLoaded] = useState(false);
   const [challengingGameAssoc, setChallengingGameAssoc] = useState(null);
   const [declinedMsg, setDeclinedMsg] = useState('');
+  const [waitingCountdown, setWaitingCountdown] = useState(0);
   const declinedTimerRef = useRef(null);
 
   const addPlayer = useCallback(entry => {
@@ -111,6 +112,7 @@ const OnlinePlayersDialog = ({ open, onClose, currentGameAssoc }) => {
       setChallengingGameAssoc(null);
       clearTimeout(declinedTimerRef.current);
       setDeclinedMsg('Challenge was not accepted.');
+      setWaitingCountdown(0);
       declinedTimerRef.current = setTimeout(() => setDeclinedMsg(''), 3500);
     };
     window.addEventListener('challenge-declined', handler);
@@ -120,15 +122,30 @@ const OnlinePlayersDialog = ({ open, onClose, currentGameAssoc }) => {
     };
   }, []);
 
+  useEffect(() => {
+    if (!waitingCountdown) return;
+    const interval = setInterval(() => {
+      setWaitingCountdown(prev => {
+        if (1 >= prev) return 0;
+        return prev - 1;
+      });
+    }, 1000);
+    return () => clearInterval(interval);
+  }, [waitingCountdown]);
+
   const handleChallenge = player => {
     if (challengingGameAssoc) return;
     setChallengingGameAssoc(player.gameAssoc);
     setDeclinedMsg('');
+    setWaitingCountdown(30);
     fetch('/api/game/challenge/' + player.gameAssoc, {
       method: 'POST',
       headers: { 'Content-Type': 'application/json' },
       body: JSON.stringify({ challengerGameAssoc: currentGameAssoc }),
-    }).catch(() => setChallengingGameAssoc(null));
+    }).catch(() => {
+      setChallengingGameAssoc(null);
+      setWaitingCountdown(0);
+    });
   };
 
   const visible = players
@@ -147,7 +164,12 @@ const OnlinePlayersDialog = ({ open, onClose, currentGameAssoc }) => {
   }
 
   return (
-    <Dialog open={open} onClose={onClose} sx={DIALOG_SX}>
+    <Dialog 
+        open={open} 
+        onClose={waitingCountdown > 0 ? undefined : onClose} 
+        disableEscapeKeyDown={waitingCountdown > 0}
+        sx={DIALOG_SX}
+      >
       <div className="opd">
         <div className="opd-header">
           <div className="opd-header-text">
@@ -160,32 +182,44 @@ const OnlinePlayersDialog = ({ open, onClose, currentGameAssoc }) => {
           <div className="opd-header-actions">
             <button
               className={`opd-refresh${loading ? ' opd-refresh--spin' : ''}`}
-              onClick={() => setRefreshKey(k => k + 1)}
-              disabled={loading}
+              onClick={() => { if (waitingCountdown === 0) setRefreshKey(k => k + 1); }}
+              disabled={loading || waitingCountdown > 0}
               aria-label="Refresh"
               title="Refresh list"
             >
               <i className="fa fa-refresh" />
             </button>
-            <button className="opd-close" onClick={onClose} aria-label="Close">
+            <button 
+              className="opd-close" 
+              onClick={() => { if (waitingCountdown === 0) onClose(); }} 
+              disabled={waitingCountdown > 0}
+              aria-label="Close"
+            >
               <i className="fa fa-times" />
             </button>
           </div>
         </div>
-        <div className="opd-search-wrap">
-          <i className="fa fa-search opd-search-icon" />
-          <input
-            className="opd-search"
-            placeholder="Search by username…"
-            value={search}
-            onChange={e => setSearch(e.target.value)}
-          />
-          {search && (
-            <button className="opd-search-clear" onClick={() => setSearch('')}>
-              <i className="fa fa-times" />
-            </button>
-          )}
-        </div>
+        {0 < waitingCountdown ? (
+          <div className="opd-waiting">
+            <i className="fa fa-hourglass-start" />
+            <p>Waiting {waitingCountdown} second{1 === waitingCountdown ? '' : 's'} for opponent's answer...</p>
+          </div>
+        ) : (
+          <div className="opd-search-wrap">
+            <i className="fa fa-search opd-search-icon" />
+            <input
+              className="opd-search"
+              placeholder="Search by username…"
+              value={search}
+              onChange={e => setSearch(e.target.value)}
+            />
+            {search && (
+              <button className="opd-search-clear" onClick={() => setSearch('')}>
+                <i className="fa fa-times" />
+              </button>
+            )}
+          </div>
+        )}
         <div className="opd-list">
           {loading && (
             <div className="opd-empty">
diff --git a/assets/js/mine-seeker/components/index.js b/assets/js/mine-seeker/components/index.js
index 06c59b5..6e8c095 100644
--- a/assets/js/mine-seeker/components/index.js
+++ b/assets/js/mine-seeker/components/index.js
@@ -10,6 +10,7 @@
 export { GameBoard } from './GameBoard';
 export { default as OnlinePlayersDialog } from './OnlinePlayersDialog';
 export { default as WaitingOverlayContent } from './WaitingOverlayContent';
+export { default as ChallengeCountdown } from './ChallengeCountdown';
 export { default as GameTimer } from './GameTimer';
 export { default as GridControl } from './grid/GridControl';
 export { default as GridField } from './grid/GridField';
diff --git a/assets/js/mine-seeker/hooks/useServerCommunication.jsx b/assets/js/mine-seeker/hooks/useServerCommunication.jsx
index cd35913..f94d9f7 100644
--- a/assets/js/mine-seeker/hooks/useServerCommunication.jsx
+++ b/assets/js/mine-seeker/hooks/useServerCommunication.jsx
@@ -14,7 +14,8 @@ import { DESC } from '@mine-utils';
 import useStepTimer from './useStepTimer';
 import { WaitingOverlayContent } from '@mine-components';
 
-/** Handles all server communication: SSE (Mercure), REST calls, and the initialization lifecycle. */
+import { ChallengeCountdown } from '@mine-components';
+
 const useServerCommunication = (gameAssoc, gameInherited, isEnvDev) => {
   const {
     /** Async-safe refs */
@@ -136,8 +137,10 @@ const useServerCommunication = (gameAssoc, gameInherited, isEnvDev) => {
 
   const wChallenge = payload => {
     const { challengerName, challengerGameAssoc } = payload;
+    let declineTimeout = null;
 
     const handleAccept = () => {
+      clearTimeout(declineTimeout);
       fetch('/api/game/challenge/respond/' + challengerGameAssoc, {
         method: 'POST',
         headers: { 'Content-Type': 'application/json' },
@@ -148,6 +151,7 @@ const useServerCommunication = (gameAssoc, gameInherited, isEnvDev) => {
     };
 
     const handleDecline = () => {
+      clearTimeout(declineTimeout);
       fetch('/api/game/challenge/respond/' + challengerGameAssoc, {
         method: 'POST',
         headers: { 'Content-Type': 'application/json' },
@@ -162,12 +166,11 @@ const useServerCommunication = (gameAssoc, gameInherited, isEnvDev) => {
       }).catch(() => {});
     };
 
+    declineTimeout = setTimeout(handleDecline, 30000);
+
     showOverlay(
       challengerName + ' wants to challenge you!',
-      <div className="resign">
-        <a onClick={handleAccept}>Accept</a>
-        <a onClick={handleDecline}>Decline</a>
-      </div>,
+      <ChallengeCountdown onAccept={handleAccept} onDecline={handleDecline} />,
     );
   };