At the moment I found that NopCommerce doesn't allow to place order on failed payment using credit cards. Just because you adding errors into processPaymentResult if payment refused or came back with error.
(We developed plugin for our Payment Gateway)
A lot of companies need the next feature: Order have to be created even with refused credit card payment.
Logic is simple: Payment Gateway return for example "Refused" payment status and the reason. In one hand, i can just not to add errors into the processPaymentResult. That prevent NopCommerce to set processPaymentResult.Success to False. And allow to place order;
In other hand, I don't want to loose important information about payment refusion. I'd rather create order an put that information into the order notes.
What about to give a custimer X chances to change credit card details (might be he will spot mistake, or will try to use different credit card). And, if after x tryings payment still not successful, place an order anyway, but give notice for customer (on order complete page, order details page and by e-mail) that payment have been not successfull.