Valve has rolled out the Steam Inventory Service in beta, allowing game developers the option to create in-game items that can be traded and sold throughout the greater Steam Marketplace.
A post on Steam News details the pre-release launch of the new feature set:
“With this service, a game can easily drop items to customers based on playtime or can grant items based on specific situations or actions within the game. These items can be marked as tradable through Steam or sellable via the Steam Marketplace. Developers can also configure recipes for crafting different combinations of items that result in more rare, unique, or valuable items.”