In the case of The Elder Scrolls IV: Oblivion an open-ended, sandbox, Lord of the Rings style fantasy game complete with swords and magic, goblins and trolls tangible content includes such things as weaponry, armour, interactable non-player characters (NPCs), quests, dungeons, castles, landmass and so on and so forth.
Normally this is software that the developers of the game have used to add actual tangible content to a game world. A lot of modern day PC video games, the sort you buy off-the-shelf at your local store, come with a piece of software known as a Software Development Kit (SDK).
