Betway is regulated by Malta and powered by Microgaming casino games. Both Malta and Microgaming do not accept citizens from the United States of America.
I sent an email to the Betway support to get a clear explanation. Here is their answer :
Thank you for contacting Betway Suport
Kindly be advised that due to US government law we do not accept US citizens. You would need to be outside the US to play on our casinos. You also need to make sure that your bank cards, proof of address and identification details are not registered in the US as this would make withdrawasl impossible for you.
Should you require any further assistance please feel free to contact our friendly help desk. We are available 24 hours a day, 7 days a week for your convenience.
As part of the US gambling law, Betway preferred to step back from the US Markets. However, some online casinos still continue to accept US citizens. Check our top 3 US Casinos.
Technically, you could play to Betway if you signed up from abroad. For instance if you are in vacation in Vietnam or in Mexico, you could play to Betway while you drink your Mai Tai. However, you should not use a US address and an american credit card (from Wells Fargo for instance).
This is the same problem as "signing-up from abroad". You could use a VPN to play to Betway, but you would need to have a real address outside of the US (with phone bill at your name for instance). If you have a sister abroad, for instance in the Brazil, it could work. Otherwise, in case you win a $9,000,000 jackpot, Betway could block your funds..
We know that Bovada is currently accepting US citizens. It is powered by Top Game software and offers a nice welcome bonus.