Some of these games have an element known as a collectible asset. (Not all of them)

If you buy an asset within the game you can later resell it when it has more value. Therefore, this can be considered an investment.

Here is an example. Say you buy a ZED racehorse... for 0.4Eth and say it wins a few races later. You can then sell it for say 4Eth on the marketplace. That's a solid return on investment!

It's an interesting concept, why put money into an unknown ICO or Protocol when you can back an asset that you own. (Some of these games are built on NFT frameworks) More here: https://en.wikipedia.org/wiki/Non-fungible_token

The idea is if you buy an in-game asset and hold it, it can become more valuable. Here is an older example where users who invested their money is buying early assets made a lot of money later. https://www.theverge.com/2017/12/13/16754266/cryptokitties-ethereum-ether-game-cats

In my opinion, these 5 games are indicating similar trends.