Image: Valve / Kotaku Yesterday, Valve issued an update for devs who sell on their storefront. Starting September 1 of this year, “banner images,” referred to as “Capsules” in Steamworks, will be restricted from including a variety of accolades, current sales, and more. In the announcement of the policy change, the house of Gordon Freeman states that the previous rules weren’t defined well enough. Banner images are the equivalent of cover art on Steam. They’re what you see in the listings on the store and they’re usually designed to get your attention as quickly as possible: That often means fancy art, a prominent main character, and the title in big,…