Milkmaid Of The Milky Way.
Official</a>
Steam
Release Trailer
(And I saw to querying about this game on de adventuregamers forums, so I wonder what happened with that. Honestly, there are a lot of point&click adventure games not on gog that would be a good fit for your store. Especially those that can't be found drm-free anywhere else yet, as is the case of this game as far as I know).