I tried one streaming game and had no problem with it. With streaming games you don't have to download them, you don't buy them individually (the monthly fee that you pay allows access to all streaming games), and they don't end up in a Purchase History. It's a bit like watching YouTube videos - you can just play/watch whatever you choose. If you want to replay something, you just start it over again.
Here is the information from Big Fish about streaming games.