A few weeks ago Valve announced that the company will be launching a free app that lets you play your Steam library on iOS and Android devices, as long as the devices are on the same network.
The Steam Link app is set to be released officially in the week of May 21, but the company has launched an open beta this weekend to test the service.
The service apparently works very well, being able to stream games up to 4K if your network and device are up to it. The app also lets users stream games to Android TV and other Android-based set-top boxes as long as they have Android 5.0 or above.
To control the game you need a Bluetooth LE controller such as the Steam controller, which may limit the market a bit.
Find the Steam Link app in the Google Play Store here.