GamersGate / GamersGate UK has finally released their VOID service. It’s basically a bunch of games that are available for Free play. You sign up for a membership and by default you are given one slot. You can fill that slot with one of the free games and you can play it all you want until a certain expiration date.
Once that expiration date arrives you can swap the game out for another or you can continue playing the same game for as long as you want.
You can add in extra slots. I’m guessing by paying a fee of some sort. The way they describe the slots it’s almost like achievements for games. Maybe it’s free somehow. There’s a cooldown period for slots also, which can also be upgraded to decrease the cooldown.
The service is free because before you play the game you have to watch a 60 second video advertisement.