Valve has introduced a dedicated page outlining what types of advertising are allowed and disallowed on its platform. The guidelines aim to guide developers in understanding what constitutes “advertising” in their games. According to the policy, product placement is permitted as long as it’s not disruptive and fits within the game context. Cross-promotions are also encouraged, but charging other developers for participation or access to a sale page is not allowed.
In contrast, paid advertising as a business model that requires players to watch or engage with ads to play or access content is prohibited. Valve emphasizes this point, stating it should be removed before a game is released on Steam. The company also advises against rewarding players for watching in-game advertisements. These updated guidelines aim to provide clarity and ensure a more respectful gaming environment for users.
Source: https://www.gamesindustry.biz/valve-implements-dedicated-page-for-advertising-guidelines