diff --git a/src/game.cc b/src/game.cc
index abe6613..648e501 100644
--- a/src/game.cc
+++ b/src/game.cc
@@ -65,6 +65,7 @@
 #include "trait.h"
 #include "version.h"
 #include "window_manager.h"
+#include "window_manager_private.h"
 #include "worldmap.h"
 
 namespace fallout {
@@ -168,6 +169,20 @@ int gameInitWithOptions(const char* windowTitle, bool isMapper, int font, int a4
         showSplash();
     }
 
+    // CE: Handle debug mode (exactly as seen in `mapper2.exe`).
+    const char* debugMode = settings.debug.mode.c_str();
+    if (compat_stricmp(debugMode, "environment") == 0) {
+        _debug_register_env();
+    } else if (compat_stricmp(debugMode, "screen") == 0) {
+        _debug_register_screen();
+    } else if (compat_stricmp(debugMode, "log") == 0) {
+        _debug_register_log("debug.log", "wt");
+    } else if (compat_stricmp(debugMode, "mono") == 0) {
+        _debug_register_mono();
+    } else if (compat_stricmp(debugMode, "gnw") == 0) {
+        _debug_register_func(_win_debug);
+    }
+
     interfaceFontsInit();
     fontManagerAdd(&gModernFontManager);
     fontSetCurrent(font);