Steam will no longer allow the hosting of games that allow the trading of NFT (non-playable tokens) and cryptocurrencies over the blockchain. The Steam page for Steamworks users and partners now specifies that they must not publish to Steam “applications built on blockchain technology that release or allow the exchange of cryptocurrencies or NFTs.” This rule was added at some point after October 6, according to the version of the page cached by Google.

Several developers have commented on this rule. SpacePirate Games, the studio behind the sci-fi action game Age of Rust, said Valve is removing blockchain games from Steam “because NFTs have value.” Some of the puzzles in Age of Rust, which is in development, will reward NFT players as achievements.

“The point of view of Steam is that such items have value, and they do not allow items on their platform that may have real value,” said a spokesman for SpacePirate. The developer plans to publish the game elsewhere.

It is unclear how many games already on Steam will be affected. Searching for the words “NFT” and “cryptocurrency” gives 14 and 64 results, respectively. However, not all of them necessarily allow you to trade in the real world. Crypto Mining Simulator, for example, lets you imagine that you are mining cryptocurrency, which is a pretty crazy idea in itself.