CITADEL is a real-time top-down game set in the flooded undercroft of an immense ancient fortress. Move with W A S D or arrow keys. Attack with J. Sidestep, the dodge, with Space or L. Use your body ability with K. Interact or possess with E. Pause with Escape. CITADEL has an original generated soundtrack, synthesised in the browser: there is no audio file in this build and nothing is downloaded. It has three parts — a quiet exploration loop, a denser combat layer that fades in over the top of it when something dangerous is close rather than replacing it, and separate, faster boss music for the chamber 10 gatehouse. No sound of any kind is produced until you press a key or click, and all of it is optional. Press M to mute everything, N to turn off the music alone and keep the sound effects, and left or right square bracket to lower or raise the music volume in steps of ten percent. The same controls are checkboxes and a slider on the title screen and the pause screen, every change is announced aloud, and the bottom-left panel of the heads-up display always states whether all sound is muted, the music is off, or the music volume as a percentage. Your status, health, remaining Holds, marked hosts and foes are announced as they change. Sidestep is a short burst of 44 pixels in the direction you are moving, or the direction you are facing when you stand still, during which you cannot be hurt for 0.24 seconds. You hold 2 Sidestep charges and one comes back every 1.4 seconds; the heads-up display shows them as two upright blue bars, reads out how many are ready, and says so aloud if you press the key with none left. Space and L are equal bindings, so a hand that cannot reach the spacebar loses nothing; a three-button mouse can use the middle button instead. Interact and Possess are on E alone and no longer share the spacebar, so the dodge key can never take a host by accident. Every body has the same Sidestep, including the starting knight, it costs no Hold, and a newly possessed body arrives with both charges. A ghost has no Sidestep, because nothing in the game can hit a ghost; only the Dwindle can end one. The game runs on a single tempered difficulty baseline; there is no mode to choose. Chambers 1 and 2 of a depth are unchanged and hold two foes; from chamber 3 onward the wards fill quickly, and chamber 9 of a depth holds nine foes. Every foe is somewhat faster, tougher and harder-hitting than before, and every wind-up is somewhat shorter, but no attack in the game lands without a drawn warning first and one Sidestep is always enough to leave one. You start as the knight, a free body of 120 hit points, holding 3 Holds, and you can never hold more than 4. Each possession spends one Hold, so a clean run gives you four bodies in total. Clearing a ward restores 5 percent of the health you lost during it, so taking no damage in a ward means no heal, and a newly possessed body always starts at full health. When a body dies you become a ghost with a 14 second Dwindle countdown, announced aloud from 5 seconds down to 1; reaching a marked host and pressing E before it expires puts you in that host. If every marked host in the ward is already dead when you become a ghost, the sigil moves to the nearest living foe that can carry it, and that is announced too, so a countdown is never unwinnable while a possible host still breathes. Sigil Fonts, which grant one extra Hold, appear in chambers 3, 6 and 9. Every foe you kill is worth 5 gold, a flat rate that never changes and is the same for a Marrow Thrall and for a gatehouse boss; your purse and that rate are both shown in the heads-up display and the total is announced when it changes. Clearing a normal chamber carries a 35 percent chance that a shopkeeper, the Hooded Factor, appears near the Warded Gate; the chamber 10 boss fight never has one. The Factor is harmless: it has no attack, it cannot be hit, and it is not part of the foe count. Walk to it and press E to trade. It stocks two ordinary weapon upgrades for the body you are currently wearing. All ten bodies have their own pair — the knight, the Marrow Thrall, the Sump Brute, the Fen Spitter, the Iron Penitent, the Gloom Cur, the Rot Sac, the Sump Slime, the Slime Spawnling and the Thorn Oracle — one that raises the damage of that body's weapon and one that suits how it fights: more reach and a wider arc for the heavy melee bodies, a faster swing or spit for the quick ones. Each piece can be bought once per run and its name, price and exact effect are read out when the stall opens. Press 1 or 2 to buy the first or second piece, or activate its button; press E or Escape to leave and keep every coin you did not spend. Beside the ordinary pair the Factor also shows two MAGICAL workings for that same body, and these obey an extra rule, which is read out every time the stall opens. You may buy only ONE of the two for that body, for the whole run. One of the pair is always the durable path, which adds maximum health and resistance, and the other is always the keen path, which adds damage, speed or a shorter ability cooldown and always charges a cost somewhere else, usually in maximum health or resistance. Buying either one immediately and permanently locks the other for the rest of the run: there is no refund, no swap and no later stall that sells it back. The path you took is shown as a solid violet row marked with a filled diamond and the word CHOSEN, and its button is disabled; the path you locked yourself out of is shown struck through and dimmed, marked with a cross and the word LOCKED, its button is disabled too, and pressing its number says out loud that it is locked and which path you took instead. A locked path can never be bought and no gold is taken when you try. Every body has its own separate pair and its own separate choice, so a run can hold up to ten of these decisions, and a body whose path is already spent is a reason to go and wear a different one. Unspent gold is kept for the whole run, across chambers and down into the next depth, and both the gold and every upgrade reset when a new run begins. The picture shows a stone ward of the Citadel seen from above: coursed masonry walls with battlements, buttresses, arrow slits and sealed arches; engaged columns; hanging banners and wall reliquaries; drain channels, iron grates and standing sludge on the flagstones; broken statuary and dressed rubble; and one arched Warded Gate closed by an iron portcullis that lifts when every foe in the ward is dead. Each ward is named aloud when you enter it, along with a one-line description of what is in it. Solid stone always carries a bright top edge; floor decoration is always flat and dark. Every creature is drawn with a hard dark outline and its own colour, so no two are told apart by colour alone: the knight is blue-grey plate with a red crest, a visored helm, an upright sword and a round shield; a Marrow Thrall is a pale upright skeleton with lit orange eye sockets, an open ribcage and a bone shiv; a Sump Brute is a green hulk, twice as wide as it is tall at the shoulder, with tusks and a timber maul; a Fen Spitter is hunched and green with a glowing acid sac on its back and a funnel maw that opens when it spits; a Gloom Cur is the only four-legged creature, low and violet-grey with a spine ridge and a whip tail; a Rot Sac is a limbless swollen bag whose veins turn hot orange while its fuse burns; a Sump Slime is a wide low aqua dome with a dark nucleus and a dribbling bottom edge, the only blue-green creature in the game, and a Slime Spawnling is the same shape two thirds the size with no nucleus; an Iron Penitent is pale iron plate under a faceless helm with one lit slit, carrying a slab shield taller than it is — the only straight vertical edge that long in the roster; a Thorn Oracle is a bone-white mask hung in a knot of black bramble over a skirt of roots, with no legs, and it is the only creature in the game that never takes a step; and an Ember Drake is a black-scaled winged dragon with two swept horns, a wingspan wider than any ordinary creature is tall, and glowing orange fissures down its chest — the only thing in the game with wings, and the only one drawn above the floor rather than standing on it. Chamber five of every depth holds one Ember Drake. It is a miniboss: as tough as a gatehouse boss, with the same drawn health bar and name plate, and it cannot be worn and never carries a mark. It flies, which means walls and the edge of the ward stop it and nothing else does — it passes straight over pillars and standing sludge, so terrain cannot be used against it. It circles you at about eighty pixels rather than walking into you. It has three attacks and each is drawn on the floor before it lands: close in, a cone of fire in front of it; at middle range, a climb and then a dive down a drawn lane; and at long range a spread of five fireballs with walkable gaps between them, seven of them once it is badly wounded. One Sidestep leaves any of them. The drake is drawn lifted off the ground, and the shadow underneath it is where it actually is, so aim at the shadow. Killing it does not open the Warded Gate on its own: the ward still has to be cleared. There are three new foes and each is announced aloud in one sentence the first time a run meets it. A Sump Slime is slow and only lightly dangerous; it telegraphs a hop with a filling arc, and when it is taken to half health it divides. The divide is warned by a growing ring and a bright seam through its body, and it produces two Slime Spawnlings; Spawnlings are a different creature entirely and can never divide again, so the population is capped at three bodies per Slime. Killing a Slime during the divide warning prevents the split. A divide is announced by a toast and pays no gold; the two Spawnlings pay five gold each. An Iron Penitent is armoured and keeps a shield across its front. Any blow arriving inside a 132 degree frontal cone is cut to a fifth and rings off with a bright metallic clang, drawn as a steel arc in front of it and flashing white on the frame it turns a blow; blows from the flank or the back land in full. It winds up a shield-bash for eight tenths of a second down a lane drawn on the floor, charges the angle it locked at the start of that wind-up so stepping sideways always beats it, and then stands with its guard completely down for one and three tenths of a second, drawn as a broken dashed arc where the solid one was. That recovery is the window to hit it. The first time a blow of yours is turned, the reason is announced aloud. The Iron Penitent is also possessable: it is the slowest body in the game at 52 speed, the toughest at 135 hit points and 30 percent resistance, it keeps a weaker version of the same frontal guard while you wear it, and its ability on K is AEGIS BASH, a short armoured lunge that damages and throws back everything in a wide arc in front of it and makes you untouchable for its whole length. A Thorn Oracle is rooted and never moves. Every three and a half seconds it raises its arms for six tenths of a second and then marks two circles on the floor near you, or three once it is below half health. Each circle sits for one and one tenth seconds filling in before thorns erupt from it, which is the longest warning of any attack in the game outside a gatehouse. Circles are placed at where you are, never at where you are going, so walking out is always an answer. Thorns hurt other foes standing in them too. Every six seconds an Oracle also mends every wounded foe within 92 pixels of it by 14 percent of that foe's maximum health, announced by a rising two-note chime and a toast; it never mends itself and never mends a gatehouse boss. It goes on mending while you are a ghost. It has only 46 hit points, so an Oracle is usually the first thing to kill. Chamber 10 of every depth is a gatehouse holding one of three bosses, rolled when the chamber is generated and named aloud as you enter, with its health bar and three phase pips drawn above it and its name written over the bar. The Sump Warden, the easier of the three, is roughly three times the size of anything else, horned, amber, with two lantern eyes and a burning gut; it slams a ring around itself, spreads six acid globs in a wedge, and charges down a straight lane. The Drowned Castellan, the middle one, is a tall narrow verdigris figure under a crown of gaol keys with two cold eye-lights; it refuses to be stood next to and backsteps when you close, fires a rotating spiral of globs, lances a drawn straight line, and sends a full ring of ten globs outward that you must already be moving between. The Ashen Marshal, the harder one, is scorched plate over a garrison-red chevron with twin blades held out and a lit visor band; it closes on you, cleaves a forty pixel arc and immediately answers it with a riposte swept back the other way, lunges down a tracked line, and stamps a fifty-two pixel circle around itself. Every attack any of the three makes is drawn as a ring, wedge, line or spoke that fills in over its wind-up before it lands, and one Sidestep is enough to leave any of those footprints. Each boss also summons its own marked hosts, capped at four alive at once, so a death in a gatehouse is still recoverable. The Hooded Factor is drawn as a tall cloaked figure in deep indigo with the hood pulled forward over a black void, two small jade eye-lights inside it, a pale stole down the front and a bulging leather bag of goods at its left side, standing in a soft pool of jade light. Three Lamplings — small winged spirits, pale jade, with hooked wings that beat, dark eye slits and no legs — float in a slow ring around its shoulders. Nothing about the stall is drawn in the orange, red or gold that belongs to enemy telegraphs, and it only ever appears in a ward that is already clear, so it can never be confused with something winding up an attack. Every creature in the game except the three gatehouse bosses can be possessed and worn. The nine that can are the Marrow Thrall, the Gloom Cur, the Sump Slime, the Slime Spawnling, the Fen Spitter, the Iron Penitent, the Sump Brute, the Thorn Oracle and the Rot Sac, and with the knight you start in that makes ten bodies. The Sump Warden, the Drowned Castellan and the Ashen Marshal can never be possessed, at any depth, on any seed; the game refuses them twice over, by leaving them out of the list of possessable types and by refusing anything flagged as a boss. Each body has its own health, speed, damage, ordinary attack and one ability on K, and each is announced aloud with its strength and its weakness the moment you put it on. The knight has 120 hit points and is balanced, and its Bulwark raises heavy resistance but slows it to a walk. The Marrow Thrall has 60 and the quickest blade, and Skitter is a short untouchable dart. The Sump Brute has 150 and the hardest blow on the slowest swing, and Quake stamps the ground all around it. The Fen Spitter has 65, fights only at range and has no melee attack at all, and Spray throws five globs at once. The Iron Penitent has 135, the highest resistance and the frontal guard, and Aegis Bash is an armoured lunge. The Gloom Cur has 58, is the fastest body in the game, has no resistance and the narrowest swing arc, and Ripline is a long committed rush that rakes everything in the lane it crosses. The Rot Sac has 70, is slow and heavy, and Rupture is the largest burst in the game and costs a tenth of your own maximum health each time, though it can never reduce you below one. The Sump Slime has 125 and real resistance but the lowest damage of any body, and Caustic Wake lays pools of acid that burn foes and never you. The Slime Spawnling has 34, the least of anything, with the shortest reach and the feeblest blow but the fastest swing in the game, and Slip is a long untouchable skip on a two second cooldown. The Thorn Oracle has 90, is the slowest body and has the longest reach, Thorn Circle plants a warned patch of thorns that hurts foes only, and it mends itself slowly while it stands perfectly still, which is the only healing in the game outside a ward clear. About one normal chamber in five also contains an empty suit of armour: a suit of plate on an iron stand with a hollow visor and no eye-light behind it, the only possessable thing in the game that was never alive. It wears the same violet diamond and violet ground-ring a marked host wears, glows faintly in the dark, and is announced when you become a ghost in a chamber that has one. As a ghost, walk to it and press E to climb in and stand up as the knight, with the knight's ordinary attack, Bulwark, ordinary upgrades and magical paths. It costs one Hold exactly like any other possession, it can only be used once, and it never appears in a chamber 10 boss fight, at any depth, on any seed. It is deliberately rarer than living hosts, which every normal chamber guarantees three of. In ghost form you are a pale blue wisp with hollow eyes and a ragged hem, and you cannot attack. A marked, possessable host wears a violet diamond hanging from a shackle bar above its head and a violet ring at its feet. The body you are currently wearing is picked out by a pale cyan ember above its head and a cold pool of light at its feet. An attack about to land is shown by an arc, line or circle that fills in as the wind-up runs out; the circle around a lit Rot Sac is its exact blast radius. While you Sidestep, the body you are wearing leaves a short trail of fading copies of itself along the path it took, and wears a dashed pale ring for exactly as long as you are untouchable, so being invulnerable is shown as a shape rather than as a flicker. Both are steady, not flashing, and both are reduced but never removed when reduced motion is on.