Shatterkin is good.
It's a take on monster collecting that, in my opinion, leans more towards Digimon than Pokemon. As opposed to collecting a massive roster of monsters your character has a single partner. This detracts from what most people might consider monster collecting but if you adjust your expectations you can get a lot out of this game.
Forged in the Dark games, in general, are robust in terms of fictional play, where the emphasis is on fictional positioning. And Shatterkin is no exception. There's a lot of innovations to the system and influences that are used well, the inherent ability/resource from Band of Blades for instance is used really well, I like the introduction of cards to represent the evolution of your shatterkin, giving you an easy to access list of traits or gear to use. Each type of shatterkin is represented via their own playbook, which makes sense as the story is about the intermingling of your normal kids and their experience with these wacky creatures.
I recommend Shatterkin if you're interested in creating stories like Digimon or Animorphs where you're wanting to explore the position of children who have the power to change the world they're in. Or even stories that are much lighter and styled after Saturday morning cartoons.
The game is still in development but I think there's a lot to chew on here and is worth investing in.