Shadow Complex is a side-scrolling action-adventure game presented in a 2.5D style, where the world is rendered in three dimensions but movement stays on a two-dimensional plane. Drawing heavily on the Metroidvania tradition, players explore a large, interconnected underground complex, fighting enemies and gradually gaining new weapons and abilities that open up previously unreachable areas. An experience system lets the character grow stronger over time, rewarding exploration and combat with upgrades that carry forward into new playthroughs.