Fix number of spaces after period

src/game.cpp

@@ -1176,7 +1176,7 @@ bool game::cleanup_at_end()
                 bool decided = false;
                 std::string buffer = _( "Warning: NPC interactions and some other global flags "
                                         "will not all reset when starting a new character in an "
-                                        "already-played world. This can lead to some strange "
+                                        "already-played world.  This can lead to some strange "
                                         "behavior.\n\n"
                                         "Are you sure you wish to keep this world?"
                                       );