Demons of Asteborg is an action-platformer with Metroidvania elements. Players control Gareth, a knight of the royal guard, tasked with stopping the villain Zadimus from destroying Asteborg. The game involves learning spells, collecting gold for upgrades, and confronting powerful bosses. Exploration spans diverse environments including woods, mountains, and swamps, as players uncover Gareth's past.

The gameplay loop centers on combat and exploration, with Gareth's abilities expanded through learned spells and purchased upgrades. The game draws inspiration from the 16-bit era of gaming.