The Citadel casts the player as a Martyr, one of the Battlesisters, sent to descend into the Citadel and confront the Sleeping God. Its identity is rooted in old-school, action-focused shooting, with a deliberately demanding tone that evokes classic 1990s shooters. The journey is organized into episodes and levels, with secret stages and formidable bosses adding further challenges.
Combat centers on dodging enemy projectiles rather than relying on hitscan attacks, making positioning and timing essential to survival. A varied arsenal includes weapons with secondary-fire functions, alongside single-use special weapons; some weapons can also be upgraded or replaced with stronger versions. The game adds close-quarters choices too: lighter enemies can be kicked and stunned, and careful positioning can send them into lava or a pit. Optional settings allow leaning and weapon-condition rules, including the possibility of automatic weapons jamming or breaking.
Unlimited continues and hub areas provide ways to persist through difficult sections without changing the game’s demanding combat design. The Citadel is listed as single-player, so its format is a solo campaign rather than a multiplayer mode; that context helps frame any player-count information as a measure of activity around an individual shooter, not a shared-session experience. Its blend of punishing projectile combat, weapon variety, and grotesque enemy defeat animations gives the campaign a forceful, retro-styled character.
