A common complaint I hear about Mario games is that they are very safe and you always know what you're going to get and I feel it is A Hat in Time's core desire to fix this.
I've never played a game with more charm and life than this. (maaaaaaaaaaaaaybe Mario Odyssey but it's very close) This game just oozes fun with every level and these levels themselves are so diverse that you will never see what's next coming. One moment you'll be racing a Mafia goon riding a rocket and right after you'll be stealing a cruise ship for adorable seals and crashing it into an iceberg.
The game is a clear love letter to classic 3D platformers, mainly from what I can tell Super Mario Sunshine more than anything else. There are even secret levels based on the FLUDDless missions from Sunshine for those who want jump straight up platforming goodness which this game also excels at. The core platforming of the game is extremely fluid and satisfying. There isn't much challenge but there are a few difficulty spikes throughout but nothing that will stop you for very long. If you want a challenge you'll want to check the Seal the Deal DLC which includes 38 extremely difficult challenge levels.
Overall this quirky game serves as an amazing platformer that solely exists just to put a smile on the face of whoever plays it. A definite modern classic.