Valve has introduced new rules for their game developers, to reverse trends that most gamers may not have realized was already happening on their platform.

As reported by GamingOnLinux, they have revised their rules to ban games that require to to watch ads to keep playing. They use this language on the revisions:
“Developers should not utilize paid advertising as a business model in their game, such as requiring players to watch or otherwise engage with advertising in order to play, or gating gameplay behind advertising. If your game’s business model relies on advertising on other platforms, you will need to remove those elements before shipping on Steam.
Some options you could consider include switching to a single purchase “paid app,” or making your game free to play with optional upgrades sold via Microtransactions or Downloadable Content (DLC).
Developers should not use advertising as a way to provide value to players, such as giving players a reward for watching or engaging with advertising in their game.”
Valve also touts that “Applications with advertising-based business models” are banned on their platform. As GamingOnLinux editor Liam Dawe pointed out, this doesn’t rule out all kinds of advertising from coming up on Steam games. But these would appear in the form of cross promotions between games and product placement. Valve also makes it clear that blockchain games that facilitate exchanges in cryptocurrencies are not allowed.
One may assume that this was a precautionary measure on Valve’s part, but there’s reason to believe that that isn’t the case at all. We found this Steam community post from 2021 asking why a game was allowed onto Steam with this exact advertising based business model. The game in question, Krunker, is a PVP shooter with voxel graphics.
Accordingly, there is still a Krunker page on Steam, but it isn’t available to download. As it turns out, Krunker has moved to its own site, where it can be played in-browser but also has its own client.
We weren’t able to find out how Krunker was using ads to make money on Steam, if it did do that, but obviously there could have been dozens, even hundreds of other Steam games that were using ads to make money. It’s easy to cheer Valve on for when they do something right, but maybe we should be more discriminating about this attitude.
In the same way that Valve didn’t have a press release revealing these new rules, they never talked about such games appearing on Steam. This isn’t to say you aren’t allowed to like Steam or Valve anymore, but we should certainly recognize when our preconceived biases may cloud and obfuscate how we’re supposed to think and treat these game companies.