Creatures Such as We is a special case, there’s some very unique circumstances surrounding it. You’d be better to contact Lynnea directly about the specifics of her arrangement with Choice of Games. It’s not a Hosted Game, it’s unique in its place on the official games page. The reasons why it’s free aren’t because she developed it independently.
If you want to use choicescript to create games, to give them away for free, to enter contests and the like you’re free to do so. It’s easy enough to change the line about where to email bugs to. (I think that’s just editing the index.html file but I’d need to check to be sure.) As long as you don’t plan to make money, then you can pretty much do what you want.
If you do want to make money off your game, but don’t want to release it through Choice of Games’ Hosted Games platform, but would rather do it yourself, you need to come to a licensing agreement with them. I believe it’s the opposite arrangement from the one they give authors. So rather than them giving you 25% of gross profit, you give them 25% of your gross profit.
If you want to create a game, enter it into contests and then submit it to Choice of Games to be published as a Hosted Game, then there’s no reason you can’t. Just check the rules for the contests to ensure they don’t prohibit selling the game afterwards.