Valve introduces a specific page detailing advertising guidelines

Valve has established a specific page to inform developers regarding permissible advertising practices on Steam.
According to reports by GamingonLinux and SteamDB, these guidelines have been in effect for five years, initially featured on the Pricing page. Valve has now relocated its advertising policies to a dedicated section on Steamworks, offering detailed examples of permissible and non-permissible advertisements in games.
The company notes, "Steam does not feature any paid advertisements, nor are such models supported in games on the platform."
Valve acknowledges the diverse interpretations of "advertising" in games and provides examples to assist developers in understanding what is supported on Steam.
For instance, product placement is accepted on the platform as long as it is non-intrusive and contextually suitable within the game.
Valve also supports cross promotions, which are "encouraged and offer value to many customers." Importantly, the company makes clear that charging other developers to join a bundle or sell access to sales or other pages on Steam is strictly prohibited.
Valve underlines that developers should avoid using paid advertising models, such as requiring users to interact with ads to play or blocking game progression behind ads.
Games dependent on these monetization models must eliminate them before being launched on Steam. Additionally, it is stated that players should not receive rewards for engaging with in-game ads.
Recently, Valve introduced a feature that alerts players if early access games have gone without updates for a significant amount of time.