Okey, I'll browse a bit itch to find some examples in the "other" category, if anything else fail... I'll just go for trial and error.
edit: just noticed that draft project can have a public link (don't need to be set public to be shown online). I think this is that's the way to go.
edit2: it's possible to use the board community feature (or comments) with unpublished game and secret url?