Yeah that's the bit I remember when Amazon was launching their game studio. It was deep in the fine print that anything you built even on your own time was owned by them, and they got flamed pretty hard by it to remove it. Important to always check for that crap, it's usually unenforceable, but remember by unenforceable I mean "You're going up against your company's lawyers. You'd probably win, if you put up a ton of your own money to fight that the contract shouldn't be valid in court with your own high price lawyers"