(Da Twitter) non so se e' roba sempre stata gratis, ma comunque:

Dubspace https://store.steampowered.com/app/2342480/Dubspace__Chapter_1/
The Unfallens https://store.steampowered.com/app/2379620/The_Unfallens_Awakening/
Lies of Astaroth https://store.steampowered.com/app/2391310/Lies_of_Astaroth/
Machine Heart https://store.steampowered.com/app/2382610/Machine_Heart/
Battle Grid: Prologue https://store.steampowered.com/app/2184680/Battle_Grid_Prologue/
Orb Flight https://store.steampowered.com/app/2406540/Or