Hollow Knight
Hollow Knight has gotten tons of praise since its release I will only reiterate that it is one of the best metroidvanias I have ever played. It is incredibly ambitious in its goals, and succeeds in them enormously.
Hollow Knight is truly the only metroidvania I have seen that lives up to the theoretical promise of free exploration. After you get a few upgrades, you are surprisingly free to go where-ever in Hollow Knight's vast world. Sure there will be dead-ends until you need more upgrades, but often you can simply get around them another way. The path you can take through the game is absurdly variable. There's tons of replayability simply because you're unlikely to take the exact same path you did the first time. It's difficult to get "lost" simply because there's rewards in nearly every direction.
Hollow Knight's world is a masterclass in variety and worldbuilding. Each section has its own palette, enemies, and even platforming style. The Queen's Gardens is all these short little platforms surrounded by thorns while the Royal Waterways is this cramped sewer. It's not afraid to use tons of different ideas for each area.
There's just a lot to do in Hollow Knight. There's going for all the various upgrades and exploring as much as the world as you can, but other things as well. You can try fighting in the Coliseum of Fools, a marathon fighting area. But there's also all the variety of dream bosses that are essentially a bunch of optional bosses (you have to kill a certain number, but not all of them). It just adds to the freeform nature of the game.
The art is this neat painterly style. I think it looks great, and frankly looks way better than all this AAA first party stuff. The story and style is super bleak. It's actually kind of impressive how bleak they make the world, while having the world seem so alive with so much variety.
Hollow Knight is a top-notch title. There's nothing like it. It's a game changer.