Can't you use a Paypal "Buy Now" Button to sell your game? I sell things using that method.
It is easy enough to put a bit of Javascript on your site to install that button, which would transfer the user to the paypal site, and then return to one of two specified pages depending on whether the payment was successful or not. The catch is that you then have to manage scripts for allowing the download, removing the link when that is done so that others can't use it. You also have to have a stable database of who successfully bought a product so that for at least a time, you can re-supply the files if they lose them or need to re-install and didn't back up. Lastly, if you get a sudden surge of earnings, paypal may think you have a fraud going and cut you off from your funds, which is why Yoyo is no longer using paypal to receive payments.
I'd say unless you have the help or are skilled enough to fully manage this, and you are willing to risk problems with paypal, I would say you are better off with BMTMicro. It also allows people to pay with things besides paypal, just a last added benefit.