But also who doesn't have the witcher 3 by now lol.
An audience we can't exclude in analysis is the "new gamers". People turning 10-15-18 years old, newcomers to gaming... If the numbers keeps coming up, it's not only because people who already play keeps buying games, but because people who never played for various reasons are coming in.
So for newcomers, 5-10 years old free games are really interesting and they may buy on whatever store providing them free games later.
Can't say how many newcomers are spawning every year, but they can't be ignored by the stores just because "everyone have that game already".