Live long and prosper!
From the Kickstarter page:
... The only big adjustment I make with a single hero is to play up the role of allies in helping that hero out. So in Den of Darkness, instead of having Gurbin be so injured he can't help much with fighting off Blunderbore, I instead would make him more capable in the scene and able to drag Twilla while the player comes up with creative ways to save the day.
Each ally lore card also has specific information about how the ally can help the heroes and will include suggestions on how to play up allies a bit more for games with only one hero. ...