
Shadow Complex is rendered in a 2.5D style, where the environment is fully three-dimensional, but the player is restricted to two-dimensional movement, evoking the feel of a traditional side-scrolling game. While the player is limited in movement, enemies can navigate freely in all directions, and the game uses an auto-aim system to let the player target foes or objects both within and beyond the 2D plane. A laser sight is controlled via the right analog stick to assist with aiming. The gameplay of Shadow Complex draws heavily from Super Metroid and Castlevania: Symphony of the Night. Like Metroid, the game allows the player to explore a vast world, battle enemies with a range of weapons, and unlock new abilities and tools that open up previously inaccessible areas. Players earn experience points by completing missions and defeating enemies. These points contribute to character levels, each of which enhances core stats. Leveling up also grants special skills, such as increased shooting accuracy or damage resistance. At certain milestones, players receive unique rewards, including full map access and unlimited special ammunition. Starting a new game causes the player to lose all collected weapons and items, but retained is the character's experience level and the benefits it provides. Beyond the main story, the game features a series of challenge levels known as "Proving Grounds," where players must reach the exit of a room using only a limited number of items and health. Performance is measured by completion time and scoring objectives, with rankings based on these metrics. Leaderboards track scores and other stats from both the main campaign and the challenge levels online. A remastered edition and port was revealed at the 2015 Game Awards, set to launch on PS4, Xbox One, and PC.
| X360 | August 19, 2009 |
| PC | December 3, 2015 |
| XONE | March 16, 2016 |
| PS4 | May 3, 2016 |
