Does it include ATM downtime?
For added realism, from time to time the ATM should refuse to execute any transactions. When that happens you roll a special dice and the real cause can be either "we outsourced our IT and don't have a clue", "hacker intrusion and we don't have a clue" or "communication links are down" The funny part is that regardless of the dice roll, the result is the same: no transaction.
Biting the hand that feeds IT
