When Valve practically started giving away Steam Link boxes for little more than price-of-postage, I assumed that the company was stepping away from the concept of in-home streamed gaming. Today's announcement suggests the idea is very much alive and well at Valve: soon you'll be able to play games from your Steam library through most iOS and Android devices via an official and free Steam Link app.
You'll need wi-fi good enough to broadcast a smooth stream, plus a device with enough CPU grunt to decode it without stuttering, but other than that there shouldn't be too many limits to the Steam Link software outside of a few extra milliseconds of input delay. Thanks to Steam Input support, you'll also be able to pair Bluetooth game controllers (such as Valve's own Steam controller) to your handheld device, allowing you to play a much wider range of games free from the shackles of touch-screen interfaces.
The nature of the Steam Controller - intended as a semi-substitute for mouse and keyboard - should mean that it's the most universally flexible controller to use with the app, although it'll be interesting to see just how easily other devices can be paired with the system. Perhaps the recently added Nintendo Switch Pro controller mode will be supported, too? Either way, this feels like it may trip up Nvidia's plans to push the Shield tablet as a gaming must-have.
The app should allow for just about everything the Steam Link box did, up to and including playing games on the big screen, but handled entirely via software. Apple iThing owners will be able to hook their phone up to their TV via an official AV adaptor, and various options exist for doing the same with the broad range of Android hardware.
While the Steam Link app is geared towards gaming, a secondary Steam Video app is also due for launch sometime this Summer, although with no firm date pinned down. The Steam Video software will let you watch your Steam video library (a growing number of films, anime series' and more, although not something I've really dug into myself) from whatever device you have to hand.
The Steam Link app will be live on Google Play and the Apple store on the week of May 21st, although precise dates per region haven't yet been announced.