diff --git a/apps/app-frontend/src/App.vue b/apps/app-frontend/src/App.vue
index 60c353f..0189adf 100644
--- a/apps/app-frontend/src/App.vue
+++ b/apps/app-frontend/src/App.vue
@@ -19,6 +19,7 @@ import {
 	SettingsIcon,
 	SpinnerIcon,
 	UserIcon,
+	UsersIcon,
 	WorldIcon,
 } from '@modrinth/assets'
 import {
@@ -2312,6 +2313,15 @@ provideAppUpdateDownloadProgress(appUpdateDownload)
 				>
 					<LibraryIcon />
 				</NavButton>
+				<NavButton
+					v-if="themeStore.featureFlags.multiplayer_in_app"
+					v-tooltip.right="formatMessage(messages.multiplayer)"
+					data-onboarding-id="nav-multiplayer"
+					to="/multiplayer"
+					:is-primary="(r) => r.path.startsWith('/multiplayer')"
+				>
+					<UsersIcon />
+				</NavButton>
 				<NavButton
 					v-tooltip.right="formatMessage(messages.lab)"
 					data-onboarding-id="nav-lab"
diff --git a/apps/app-frontend/src/components/ui/settings/FeatureFlagSettings.vue b/apps/app-frontend/src/components/ui/settings/FeatureFlagSettings.vue
index 0790adb..6040baf 100644
--- a/apps/app-frontend/src/components/ui/settings/FeatureFlagSettings.vue
+++ b/apps/app-frontend/src/components/ui/settings/FeatureFlagSettings.vue
@@ -69,6 +69,7 @@ const featureFlagLabels: Record<FeatureFlag, string> = {
 	show_instance_play_time: '显示实例游玩时间',
 	page_transitions: '页面切换动画',
 	advanced_filters_collapsed: '高级筛选默认折叠',
+	multiplayer_in_app: '多人联机',
 	auto_install_dependencies: '自动安装依赖',
 }
 
diff --git a/apps/app-frontend/src/store/theme.ts b/apps/app-frontend/src/store/theme.ts
index 1c97433..bc6366c 100644
--- a/apps/app-frontend/src/store/theme.ts
+++ b/apps/app-frontend/src/store/theme.ts
@@ -14,6 +14,7 @@ export const DEFAULT_FEATURE_FLAGS = {
 	skip_non_essential_warnings: false,
 	skip_unknown_pack_warning: false,
 	i18n_debug: false,
+	multiplayer_in_app: false,
 	show_instance_play_time: true,
 	page_transitions: true,
 	advanced_filters_collapsed: true,