Principia: Master of Science is listed in the Steam Weekly Sale this week as part of Playism's selection of Adventure titles!
Take this chance to grab it while its on sale (August 28 - September 4)
http://store.steampowered.com/app/491470/PRINCIPIA_Master_of_Science/
Check out other titles like Mad Father and Angels of Death, also on sale this week.
PLAYISM Adventure Selection Sales list