You do have to watch out tho that it is actually a good project and they wont just disappear out of no where again, i had 1 project that looked really cool (aethia online) but eventually they just disappeared and didnt continue anymore.
Luckely I didn't put to much ethereum in it, but it was still a waste of time.
Recently there was a very good cardgame on the blockchain I really liked (Gods unchained) that has the cards on the ethereum blockchain where you can also trade them for Ethereum, I joined the beta and earned points winning games where you could sell them for ethereum which i did.
Also they had weekly tournements where you could earn packs that other people had to buy in the shop.
I thought that was a really cool idea and they even had 4 different 1 of a kind cards and they sold for a lot 60000$+
The game is still new and recently officially launched.
I think it is the future for games to have their lets say marketplace or currency on the market where you can buy ingame gold/items for cryptocurrencie that would be very cool!
there are lot's of buys/sells going on with this game:
https://opensea.io/category/gods-unchained
highest sold for 235 ETH:
https://opensea.io/assets/gods-unchained?sortBy=assets_prod_main_last_sold_desc