Valve has added a much welcomed feature to their Steam client, and that is initiate game downloads and installations remotely from any device where you can logon to Steam (Android, Web, iOS). The new feature allows users to browse the service’s catalog from a web browser and initiate downloads for new or existing purchases to their Mac or Windows PC much like Google’s Play Store or Microsoft’s Xbox Live.

The only requirement it seems is to have the latest beta build of the Steam client installed.

To install the new Beta build of the Steam client with remote game download feature:

1. Open your Steam Client and login.
2. On Windows
   go to File -> Settings
   On OSX
   Open the preferences
3. On the Account tab press the Change button to open the Beta Participation dialog
   
4. Select “Steam Beta Update”, and allow Steam to restart itself.

To start downloading remotely:

1. Login to Steam via the Steam Android App or the website
2. Visit your Games list by navigating to the Community and then clicking GAMES in the secondary navigation bar. If you’re logged into the Steam client, the games list will reflect the installation state of your library on that machine.
3. Locate your game and tap the install button to initiate your remote download.

Below is my trial run using the Android App and the Mac OS client:

After clicking the download button for Torchlight….

Hurrah

source Steam