It released, which is something most people didn't know it seems, and according to this recent thread I read on Reddit, has had plenty of issues to do with performance (poor) and paymodel (restrictive):

"project spark wasn't dead on arrival, it was dead on beta.

The horrible paymodel is just crippling to the kind of game it is.

It also runs REALLY badly, even if there is nothing complex happening. A flat plane, and an item capped world run equally poorly"

"I love the game but I cant bring myself to play it because all the good stuff is locked behind expensive micro-transactions. I wanted to try make helms deep, Oh I guess not because the castle parts pack is like $15, Oh I'll make a wild west town then? nope, the desert terrain type is equally expensive.

Its a game that at its core is a fantastic but to me its ruined by its microtransaction system. I would have rather just payed $30 for the game and have everything then the current "free" system."

"I remember messing around with Project Spark on xbone release and again a couple months ago. The game ran at about 20 FPS constant and would regularly drop below that when you actually started placing anything interesting. Because of this, the "platforming" was awful and the combat was one button nonsense. I don't really understand why anyone would spend any time developing for something that was so poorly optimized. Instead of being a true "sandbox" it felt like Microsoft's gimped version of LittleBigPlanet."

What was the overral public reception of KI anyway? I've seen people on the internet asking for KI3 for years and when it finally came... it seems not a lot of people cared about it?

Did the free-to-play nature of the game killed it or something? Or is it popular and I just don't know about it?