Being able to transfer ownership of something of a value seamlessly over decentralised network is the basic for Blockchain. More so for non-fungible assets.
Non-fungible asset is an asset unique by itself and not equate to something of a similar properties.
Normally, when we want to create asset on blockchain, first thing come to mind is create tokens, each represent one unit in real life. That would be using Mosaic in NEM. However, Mosaic is flat by its nature, hence, it is fungible. So, how to create non-fungible assets over NEM Blockchain?
Use caseA dog trainer game.
Here, I will use Account to represent each dog. Convert the account to 1-of-1 multisignature account where the owner of the dog, the player, is the sole signatory.
The player as the dog trainer needs to train the dog with different tricks and toward higher level of skill. For every trick it learns, a special mosaic will be added to the multisig account representing the dog. For example, a mosaic for rescuing people, a mosaic for climbing tree, a mosaic for swimming etc (the mosaics use here shall be non-transferrable). The account with more types of mosaic meaning the dog has learnt more skills. The greater number of same mosaics in the account means the level of skills the dog has.
The dog trainer can also sell the dog to another player. All to be done is to transfer the ownership by adding and removing cosignatory through aggregate transaction.
As I am not using Mosaic to represent the dog, hence, I do not call it non-fungible token, but non-fungible asset. This method can be used in both NIS1 and Catapult.
