Valve have updated the developer guidelines for releasing a game on Steam, making it clear that the scourge of mobile gaming advertising-based business models are not going to work on Steam.
Haven't seen a game that uses ads like this, but very good that it's strictly prohibited now. That shit should never have taken off on mobile, but alas. At least we can prevent it on PC.
If you see Google launch a "free game only" store for PC, get worried.
I would be astonished if there was anything good on it though. If you are going to make a microtransaction game you probably don't want to put a lot of effort into it because people won't play it for more than about a week. This stuff's only profitable if you can shovel new games out of the door on a regular basis.
Oh there wouldn't need to be anything actually good on it.
You just need Superbowl advert money and suddenly you've got millions of users with no money.
I suspect the only reason this hasn't happened already is that those millions of users are already on mobile, being flashed with garish noisy adverts every two minutes of gameplay, and moving them to PC some of the time wouldn't really increase ad revenue...