In each round, you and your match each simultaneously either choose Push or Pull.
In each round, you and your match each choose between Push and Pull. Your earnings depend both on your choice and your match's choice.
If you choose Pull, you add money to your earnings. If you choose Push, you instead add a greater amount of money to your match's earnings.
If your match chooses Pull, it adds money to her earnings. If she chooses Push, it instead adds a greater amount of money to your earnings.
Simple. Or is it?
If Push=$400 and Pull=$300, then choosing Push increases your match's earnings by $400, but choosing Pull increases your earnings $300. Your match also chooses between pushing $400 to you and pulling $300 to herself.