My solution to that? Continue to build my games on a Google Site, and embed the locks page onto there! That way, the clues can still be hidden all around, and the platform just takes the place of a Google Form as the lock box.
I've gotten some requests to post a follow-up to my original screencast (Creating Digital Games on the BreakoutEDU Platform) about how to embed them. Your wish is my command! This screencast shows the steps to embed an already-created digital platform game into a new Google Site.
It is also possible to embed videos into the classic Google Sites, but it's a bit less intuitive. Feel free to reach out if you are needing help in that area!