Interactable

You need to click on the button in the top-left corner in order to make the image interactable.

Source: wiktionary

There aren't many interactable objects in the game, so you shouldn't have any trouble finding the key.

Source: wiktionary

The basic elements of the message can be divided into three essential groups: visuals, audibles, and interactables. […] Interactables are the basic pieces of the multimedia application that often are described as tools. These tools include screen elements, input and output dialog devices, and navigational structures that enable you to move through the information’s architecture.

Source: wiktionary

Located at the Web site for Fork, the communications design division of IDEO Product Development, these “interactables” are messages that the reader must interact with in order to get the full experience.

Source: wiktionary