I should have played more past day 8 -- I had only memorized 3-4 recipes so I believe the difficulty still has room to ramp up over time, or else other difficulties could start with more recipes/customers from the beginning. The initial curve feels good to me though!
I would happily pay for a 2-4 kitchen local multiplayer without any expansion of the features other than displaying whomever had the high score after 7-14 days (￣ω￣)
