Block chain technology helps manage the database that records the transactions of these coins/tokens. Games that rely on blockchain technology tend to have a DECENTRALIZED marketplace for in-game items. When you buy these items, the ledger recognizes that the item is own by you and no one else! This is the power of ownership. For example, the game Etherions allow you to purchase a dragon using Ethereum via Metamask. In theory, you can trade and sell your dragons (in future updates) with other players! It's a bit similiar to trading and selling Yugioh/Pokemon Cards when you were younger. Most of these games are "card collecting" games, but major platforms are starting to expand their horizon. In theory, the rarer your items, the more profit you can sell them for. In this game, the value of these dragons depend on how rare it is and how old it is. Since training your dragons can take months, people are more likely to just purchase an adult dragons from other players. I'm not an expert, but I hope I help gave you an idea of what this is all about.