At this time I'd like to shill for Warframe.
The game is free. The battlepasses are free. The lootboxes are free. The ways you open those lootboxes are also free. The premium currency is a tradable item, so it is 100% viable to get it and buy premium shit without ever spending real money. Digital Extremes (the devs) once accidentally created a gambling machine (for pet cosmetics), and upon discovering what they did, removed it from the game and refunded everyone who spent money on it.
Warframe is the one game that I've spent more money on than any other game, I'm not biased, you're biased.