Not exactly free, but . Fanatical often runs a “Humble HOPA Bundle” where you can get 5 Artifex Mundi games for $4.99 – that’s $1 per full game. Humble Bundle does similar.
Many Artifex Mundi titles on the Microsoft Store and Big Fish Games offer extensive free trials. Unsolved - Artifex Mundi Wiki free artifex mundi full version games for pc link