Considering this is the first service of its kind, GamersGate is taking a bit of a risk. There is some good news though because ad space in Scandinavia is already sold out through July. Granted, larger regions like the US and Canada are going to be different.
How it seems to work is that you pick a game to fill a slot, of which you only have a handful. Any game in a slot can be downloaded and played from your PC for free. Naturally an ad will play before the game starts but it is unclear if there are any in-game ads. Check out the official site for the full details.
Their service doesn’t have a huge amount of games yet but this is only the first day and they promise to continue adding to the library. Void looks to be a very promising idea and I hope it catches on. It could end up being Spotify for videogames and who wouldn’t want that?