In The Kingdom (Amon26)

"In The Kingdom is a twisted retro first person shooter inspired by the classic titles like Wolfenstein, Doom, Quake, Rise Of The Triad, and Chasm. Explore the hellish ruins of a forgotten castle fortress poisoned by dark magic and evil forces. Survive to the last and discover a new destiny." - Author's description

Purchase for $5 on itch.io (Windows, Mac)