diff --git a/src/m_menu.c b/src/m_menu.c
index a9bb1fda9..5bbe9c825 100644
--- a/src/m_menu.c
+++ b/src/m_menu.c
@@ -759,17 +759,18 @@ static menuitem_t SR_EmblemHintMenu[] =
 // Single Player Main
 static menuitem_t SP_MainMenu[] =
 {
+	// Note: If changing the positions here, also change them in M_SinglePlayerMenu()
 	{IT_CALL | IT_STRING,                       NULL, "Start Game",    M_LoadGame,                 76},
 	{IT_SECRET,                                 NULL, "Record Attack", M_TimeAttack,               84},
 	{IT_SECRET,                                 NULL, "NiGHTS Mode",   M_NightsAttack,             92},
-	{IT_CALL | IT_STRING | IT_CALL_NOTMODIFIED, NULL, "Marathon Run",  M_Marathon,                100},
+	{IT_SECRET,                                 NULL, "Marathon Run",  M_Marathon,                100},
 	{IT_CALL | IT_STRING,                       NULL, "Tutorial",      M_StartTutorial,           108},
 	{IT_CALL | IT_STRING | IT_CALL_NOTMODIFIED, NULL, "Statistics",    M_Statistics,              116}
 };
 
 enum
 {
-	sploadgame,
+	spstartgame,
 	sprecordattack,
 	spnightsmode,
 	spmarathon,
@@ -8073,29 +8074,67 @@ static void M_SinglePlayerMenu(INT32 choice)
 {
 	(void)choice;
 
+
+	// Reset the item positions, to avoid them sinking farther down every time the menu is opened if one is unavailable
+	// Note that they're reset, not simply "not moved again", in case mid-game add-ons re-enable an option
+	SP_MainMenu[spstartgame]   .alphaKey = 76;
+	SP_MainMenu[sprecordattack].alphaKey = 84;
+	SP_MainMenu[spnightsmode]  .alphaKey = 92;
+	SP_MainMenu[spmarathon]    .alphaKey = 100;
+	//SP_MainMenu[sptutorial]  .alphaKey = 108; // Not needed
+	//SP_MainMenu[spstatistics].alphaKey = 116; // Not needed
+
+
 	levellistmode = LLM_RECORDATTACK;
 	if (M_GametypeHasLevels(-1))
 		SP_MainMenu[sprecordattack].status = (M_SecretUnlocked(SECRET_RECORDATTACK)) ? IT_CALL|IT_STRING : IT_SECRET;
-	else
-		SP_MainMenu[sprecordattack].status = IT_NOTHING|IT_DISABLED;
+	else // If Record Attack is nonexistent in the current add-on...
+	{
+		SP_MainMenu[sprecordattack].status = IT_NOTHING|IT_DISABLED; // ...hide and disable the Record Attack option...
+		SP_MainMenu[spstartgame].alphaKey += 8; // ...and lower Start Game by 8 pixels to close the gap
+	}
+
 
 	levellistmode = LLM_NIGHTSATTACK;
 	if (M_GametypeHasLevels(-1))
 		SP_MainMenu[spnightsmode].status = (M_SecretUnlocked(SECRET_NIGHTSMODE)) ? IT_CALL|IT_STRING : IT_SECRET;
-	else
-		SP_MainMenu[spnightsmode].status = IT_NOTHING|IT_DISABLED;
+	else // If NiGHTS Mode is nonexistent in the current add-on...
+	{
+		SP_MainMenu[spnightsmode].status = IT_NOTHING|IT_DISABLED; // ...hide and disable the NiGHTS Mode option...
+		// ...and lower the above options' display positions by 8 pixels to close the gap
+		SP_MainMenu[spstartgame]   .alphaKey += 8;
+		SP_MainMenu[sprecordattack].alphaKey += 8;
+	}
 
-	SP_MainMenu[sptutorial].status = tutorialmap ? IT_CALL|IT_STRING : IT_NOTHING|IT_DISABLED;
 
 	// If the FIRST stage immediately leads to the ending, or itself (which gets converted to the title screen in G_DoCompleted for marathonmode only), there's no point in having this option on the menu. You should use Record Attack in that circumstance, although if marathonnext is set this behaviour can be overridden if you make some weird mod that requires multiple playthroughs of the same map in sequence and has some in-level mechanism to break the cycle.
-	if (!M_SecretUnlocked(SECRET_RECORDATTACK) // also if record attack is locked
-		|| (mapheaderinfo[spmarathon_start-1]
+	if (mapheaderinfo[spmarathon_start-1]
 		&& !mapheaderinfo[spmarathon_start-1]->marathonnext
 		&& (mapheaderinfo[spmarathon_start-1]->nextlevel == spmarathon_start
-			|| mapheaderinfo[spmarathon_start-1]->nextlevel >= 1100)))
-		SP_MainMenu[spmarathon].status = IT_NOTHING|IT_DISABLED;
-	else
-		SP_MainMenu[spmarathon].status = IT_CALL|IT_STRING|IT_CALL_NOTMODIFIED;
+			|| mapheaderinfo[spmarathon_start-1]->nextlevel >= 1100))
+	{
+		SP_MainMenu[spmarathon].status = IT_NOTHING|IT_DISABLED; // Hide and disable the Marathon Run option...
+		// ...and lower the above options' display positions by 8 pixels to close the gap
+		SP_MainMenu[spstartgame]   .alphaKey += 8;
+		SP_MainMenu[sprecordattack].alphaKey += 8;
+		SP_MainMenu[spnightsmode]  .alphaKey += 8;
+	}
+	else // Otherwise, if Marathon Run is allowed and Record Attack is unlocked, unlock Marathon Run!
+		SP_MainMenu[spmarathon].status = (M_SecretUnlocked(SECRET_RECORDATTACK)) ? IT_CALL|IT_STRING|IT_CALL_NOTMODIFIED : IT_SECRET;
+
+
+	if (tutorialmap) // If there's a tutorial available in the current add-on...
+		SP_MainMenu[sptutorial].status = IT_CALL | IT_STRING; // ...always unlock Tutorial
+	else // But if there's no tutorial available in the current add-on...
+	{
+		SP_MainMenu[sptutorial].status = IT_NOTHING|IT_DISABLED; // ...hide and disable the Tutorial option...
+		// ...and lower the above options' display positions by 8 pixels to close the gap
+		SP_MainMenu[spstartgame]   .alphaKey += 8;
+		SP_MainMenu[sprecordattack].alphaKey += 8;
+		SP_MainMenu[spnightsmode]  .alphaKey += 8;
+		SP_MainMenu[spmarathon]    .alphaKey += 8;
+	}
+
 
 	M_SetupNextMenu(&SP_MainDef);
 }