Backing out of the final stage prevents getting extra stage. Backing out of extra stage (or second extra stage) fails the stage.

stepmania/src/GameState.cpp

@@ -255,6 +255,8 @@ void GameState::Reset()
 	m_stEditSource.Set( STEPS_TYPE_INVALID );
 	m_iEditCourseEntryIndex.Set( -1 );
 	
+	m_bBackedOutOfFinalStage = false;
+
 	ApplyCmdline();
 }
 
@@ -968,6 +970,9 @@ bool GameState::HasEarnedExtraStage() const
 	if( this->m_PlayMode != PLAY_MODE_REGULAR )
 		return false;
 	
+	if( m_bBackedOutOfFinalStage )
+		return false;
+
 	if( (this->IsFinalStage() || this->IsExtraStage()) )
 	{
 		FOREACH_EnabledPlayer( pn )

stepmania/src/GameState.h

@@ -144,6 +144,7 @@ public:
 	Course*		m_pPreferredCourse;
 	BroadcastOnChangePtr1D<Trail,NUM_PLAYERS>	m_pCurTrail;
 
+	bool        m_bBackedOutOfFinalStage;
 	
 	//
 	// Music statistics:  Arcade: the current stage (one song).  Oni/Endles: a single song in a course

stepmania/src/ScreenGameplay.cpp

@@ -1823,6 +1823,14 @@ void ScreenGameplay::BackOutFromGameplay()
 	m_soundAssistTick.StopPlaying(); /* Stop any queued assist ticks. */
 
 	this->ClearMessageQueue();
+	
+	// If this is the final stage, don't allow extra stage
+	if( GAMESTATE->IsFinalStage() )
+		GAMESTATE->m_bBackedOutOfFinalStage = true;
+	// Disallow backing out of extra stage
+	if( GAMESTATE->IsExtraStage() || GAMESTATE->IsExtraStage2() )
+		SCREENMAN->PostMessageToTopScreen( SM_BeginFailed, 0 );
+	else
 		m_Cancel.StartTransitioning( SM_GoToScreenAfterBack );
 }
 
@@ -2288,7 +2296,6 @@ void ScreenGameplay::HandleScreenMessage( const ScreenMessage SM )
 			float fMaxSurviveSeconds = 0;
             FOREACH_EnabledPlayer(p)
                 fMaxSurviveSeconds = max( fMaxSurviveSeconds, STATSMAN->m_CurStageStats.m_player[p].fAliveSeconds );
-			ASSERT( fMaxSurviveSeconds > 0 );
 			m_textSurviveTime.SetText( "TIME: " + SecondsToMMSSMsMs(fMaxSurviveSeconds) );
 			SET_XY_AND_ON_COMMAND( m_textSurviveTime );
 		}