GeForce Now costs $8 per month and lets you play a library of "more than 80" titles at no extra cost, with the option to pay extra to stream newer games. Provided you have the connection, it'll stream the games at 1080p and 60 frames per second. It's supported by both the Shield TV and the Shield Tablet.
Square Enix says it'll bring more games to the platform after the initial wave this year. If they all seem... somewhat similar in scope, that's not by accident: the company says that "SHIELD owners tell us that they love action-adventure games."