Just stumbled on this yesterday...the service started in May.
http://www.gamersgate.com/void
The VOID system is based on slots. Slots decide how many games you can play; for example, you need an open slot to choose and play a VOID game. The number and types of slots you have decide how many games you have available at a given time.
Once a slot is occupied by a game you can download and install it by selecting a slot with a game and clicking ’install’.
Whenever you launch a VOID game you will see a few video advertisements. Support the developers by watching them, you’re about 60 seconds from gaming!
After a set amount of days you will have the option to exchange the game in your slot for another one, or you can just keep playing the same game forever. Slots can be upgraded to quicken the cooldown and you can also get more slots!
Some of the games currently available include:
Risen
You Are Empty
Secret Files: Tunguska
Black Mirror
Oddworld: Abe's Oddysee
Cursed Mountain
Darkness Within 1 & 2
Dark Fall: Lost Souls
Dark Void
Vivisector: Beast Within
Cold War
Cold Zero - The Last Stand
Dark Void Zero
Flatout
Painkiller
Bet On Soldier
Death to Spies
Forever Worlds
Crime Stories
Next Life
Outcry
Twin Sector