We believe that this type of game is very interesting for children because it is based on everyday situations and characters. Some ideas we have come up with are to change the objective from the total amount of money to be collected to a general satisfaction level that goes up or down, and to have workday cycles with a certain number of customers (the objective being to see how many days you can keep the store open). Include a positive feedback loop so that if you manage to make several perfect returns, it accumulates with a multiplier, and a negative feedback loop so that if you fail several times, it helps you by lowering the difficulty (for example, a customer comes in who has paid the right price).