I had the opportunity to play a short session of this game not so long ago, and read a lot of intriguing praises for the book itself (mostly in a french RPG forum), so I finally bought it.
And I was amazed ! Everspark is not a mere gimmick, to me it's genius !
I don't even use this word lightly.
Reading the book made me reconsider every way I ever ran my games, for the last 34 years. It's nothing short of an epiphany, accepting to go to the raw core of what makes RPGs enjoyable for me in the first place.
Even the parts I thought I wouldn't care so much about, the building blocks you designed for us to play straight away, got to me real hard when I fiddled with them...
It might be a honeymoon kinda love for your game for now, and I swore to myself not to forsake every other game engine yet, but Everspark definitely gets gaming done right !