Amazon now offers the ability to buy games on its Luna cloud gaming service, but the new feature comes with a big catch: at least for now, you’ll only be able to buy select Ubisoft titles.

For me, Amazon was advertising games you can buy right on the main Luna homepage, including the just-released Assassin’s Creed Mirage. However, if you end up buying an Ubisoft game on Luna, you’ll need an Amazon Prime or a Luna Plus subscription to be able to stream that purchased game, according to an Amazon blog post about the feature.

The ability to buy games is all well and good on its own; previously, you could only play games on Luna by subscribing to specific channels of content, accessing a rotating set of games available to Amazon Prime subscribers, or playing Ubisoft games you already owned for PC on the cloud gaming service. According to Amazon, you’ll be able to play the Ubisoft games you buy through Luna offline on your PC, too.

But Amazon’s announcement about the new feature hints at the possibility that you can play those purchased Ubisoft games on other cloud services as well. Here’s the line in question from Amazon’s blog post and with my emphasis:

When customers purchase through Luna, they own the game license, and they will be able to play on Luna or download for offline play via the Ubisoft Connect PC launcher.

Since you own the game license, that language makes it seem like you can, say, buy an Ubisoft game on Luna, stream it for a bit on Luna, and then pick up your progress through another cloud gaming service like Nvidia’s GeForce Now. Good news: after we first published this article, Ubisoft’s Jessica Roache confirmed to The Verge that you will be able to play games you buy on Luna on services like GeForce Now (though not every game supports cross-progression).

Amazon spokesperson Sasha Mealor declined to comment, and also declined to comment when asked if it plans to let customers buy and stream non-Ubisoft games at some point in the future. Google offered the ability to buy games on Stadia, its now-shuttered cloud service.

Update October 6th, 8:54PM ET: Added Ubisoft comment.