Obsession
Should I use the Upstairs, Downstairs hire-on-pass rule or its servants when playing solo against base opponents?
No. The designer says base solo opponents are calibrated to the original passing rule, so hire-on-pass gives you a significant edge, and Upstairs, Downstairs servants raise scores too much; use the Upstairs, Downstairs solo opponents instead. If you do play Upstairs, Downstairs servants in the original solo mode, set up as two players with one of each new servant, draft one, expect higher scores and choose tougher opponents.