I've been playing a number of Netmarble games lately. The Korean company would like you to buy everything but you can still make progress without buying anything. That's the way with most of my recent freemium games.
I play Unreal Tournament 2004 daily, even though Epic Games kind of killed it and other games in the series. The only thing to come close is Toxikk, which was US$5.00 and is now free.
I bought a couple of games that were highly recommended and I couldn't believe that anyone would recommend them. That's the case of a lot I see now. On the other hand, Hi-Fi Rush is amazing and of course, Tango Gameworks has been closed. They didn't have loads of items to buy. It was just for fun.