Fate Core (which is absolutely necessary for this product, introduced a refined RPG system that focuses on story above all else. Your characters are tough and are nearly-unkillable but the can be maimed to the point of uselessness and it might be time to make a new character while your old one retires to a background character or a source of quests for revenge due to their injuries. Fate allowed players and the GM to create worlds and scenarios together leading to a great overall understanding of the universe everyone was playing in and the broad and simple rules made it a snap to learn. The big rub was that SOME things NEEDED depth, how magic works, how cybernetic enhancements would change characters, and the negative aspect of using too much of these things with one character. While Fate Core touched on how to balance stuff like this, the Fate System Toolkit refines it and offers much easier source material to fine craft the universe you and your players game in. Not only a good GM tool, the System Toolkit is best shared with players to get a good idea on how to handle the game more fluidly.