They claim to deliver the performance of a high end gaming system, through any old computer you have. They also offer a "Box" ($139) that is supposed to deliver the best experience for their service: https://shadow.tech/usen/box
This is actually the only way I'll likely be PC gaming anytime soon. Building a rig just isn't in the cards nowadays. Looks like it's the equivalent of a virtual machine with a dedicated GTX card and 12GB of RAM.