They have a couple of OSR products, most notably Battleaxes & Beasties, a retro clone, and their adventure for it, Witches of Hagswallow (Only 49 cents). It seems S&W based so pretty easy to use in other stuff.
They also have a small series of adventure locations which are more generic D&D (actually OSR and 5E) but interesting. Now only 75 cents each.
All include VTT maps.