Added option to randomize INITIAL_DAY

src/game.cpp

@@ -11406,7 +11406,11 @@ void game::start_calendar()
         }
     } else {
         // No scenario, so use the starting date+time configured in world options
-        const int initial_days = get_option<int>( "INITIAL_DAY" );
+        int initial_days = get_option<int>( "INITIAL_DAY" );
+        if( initial_days == -1 ) {
+            // 0 - 363 for a 91 day season
+            initial_days = rng( 0, get_option<int>( "SEASON_LENGTH" ) * 4 - 1 );
+        }
         calendar::start_of_cataclysm = calendar::turn_zero + 1_days * initial_days;
 
         // Determine the season based off how long the seasons are set to be

src/options.cpp

@@ -2057,8 +2057,8 @@ void options_manager::add_options_world_default()
        );
 
     add( "INITIAL_DAY", "world_default", translate_marker( "Initial day" ),
-         translate_marker( "How many days into the year the cataclysm occurred.  Day 0 is Spring 1.  Can be overridden by scenarios.  This does not advance food rot or monster evolution." ),
-         0, 999, 60
+         translate_marker( "How many days into the year the cataclysm occurred.  Day 0 is Spring 1.  Day -1 randomizes the start date.  Can be overridden by scenarios.  This does not advance food rot or monster evolution." ),
+         -1, 999, 60
        );
 
     add( "SPAWN_DELAY", "world_default", translate_marker( "Spawn delay" ),