Thank you for trying to go to work :p. Did you try slapping from the outside of the blob of NPCs? If you slapped them in the middle, it has almost no effect because there are people nearby reducing the force of the slap.
Also slapping regular boarding NPC, besides the stress level automatically increasing, is turning them into angry NPC (the red ones). And slapping the exiting NPC too much is making them slower ahahah. Sorry I made it a bit frustrating on purpose.
Regarding your character going out of screen is fine, because I made the area larger than the visible screen but sometimes boarding NPCs are just loitering around and honestly, I also found it during playtest but I thought it was a nice additional kind of obstacle.