We have not been able to find a lot of research that defines and categorises different kinds of inventory systems. This thesis expands on what makes an inventory system what it is and how different active inventory systems differ from each other. There’s a lack of non-generic language both in research and everyday discussions between friends that we aim to alleviate. We adapt and make use of an existing pattern creation method as well as an immersive-participatory method to play and analyse nine games that all make use of inventory systems in very different ways. Through this method we created three game design patterns that describe the differences in limitation and presentation within active inventory systems; allocated inventories, numerical inventories and spatial inventories.