Shadow Complex is a 2.5D side-scrolling action game, combining elements from Metroid and Castlevania: Symphony of the Night. Players explore a large 3D world, acquiring new weapons and abilities to access previously unreachable areas, while defeating enemies grants experience points and level ups for character progression. The game utilizes auto-aim and offers a 360-degree aiming system for combat, creating a seamless blend of classic and modern gameplay mechanics.