This game plays like a mix between more traditional Mario games and Mario 64.
Let me explain. You start off in an open hub world. This hub world is almost a typical Mario side-scrolling level, but with no enemies and an assortment of puzzles and places to go to find the actual levels of the game. There are at least two doors you can open at the very beginning, but when you complete them, you get a star. The more stars you have the more doors you can open. There is also a warp room you can use when you get so many stars. In this way, it is a bit like Mario 64. You've got different worlds you can go through if you've got the stars. The hub world has no enemies, a variety of NPC's to talk to, coins, and items. There also seems to be some hazards. I think you can fall to your death in the hub world, but have not ever tried it out. The NPC's do give incredibly useful hints. For example, one tells you that there is a moon hidden in each stage that gives out a lot of lives.
The levels themselves are a tad different. There are only 8 levels and they are full to the brim of enemies and diverse enemies. Even the most basic level is challenging due to the large amount of enemies. There are some puzzles that are required to be solved, but more often there is simply a diverse array of enemies creating a narrow pattern that is difficult to cope with. It may be chaotic and at times difficult to follow, but it actually provides a decent challenge without being too frustrating. I would make a compliment of how chaotic, yet enjoyable each level is. Chaos and enjoyable level design come here together as a kind of oxymoron. The difficult ramps up at a good pace.
Overall, I would heartily recommend this game to anyone who like's Mario Maker. It really is a good fan game. However, it doesn't have too much content, so it's probably only got an hour or two of gameplay in it.