All payment gateway drivers must implement the Aero\Payment\Contracts\PaymentDriver interface.
The Aero\Payment\PaymentDriver abstract class can be used as the starting point, which supports the ECOM operation mode by default.
It's important to register the payment driver with the payment processor, which is used by the checkout and admin modules. This should be done in a ServiceProvider using the following call:
\Aero\Payment\PaymentProcessor::registerDriver('my_gateway', \Acme\PaymentDriver::class);