4 files changed, 301 insertions, 30 deletions

diff --git a/Cargo.lock b/Cargo.lock
index d3682b2..2485847 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -52,7 +52,13 @@ dependencies = [
 ]
 
 [[package]]
-name = "doom"
+name = "downcast-rs"
+version = "1.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "75b325c5dbd37f80359721ad39aca5a29fb04c89279657cffdda8736d0c0b9d2"
+
+[[package]]
+name = "dungeon"
 version = "0.1.0"
 dependencies = [
  "minifb",
@@ -60,12 +66,6 @@ dependencies = [
 ]
 
 [[package]]
-name = "downcast-rs"
-version = "1.2.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "75b325c5dbd37f80359721ad39aca5a29fb04c89279657cffdda8736d0c0b9d2"
-
-[[package]]
 name = "errno"
 version = "0.3.14"
 source = "registry+https://github.com/rust-lang/crates.io-index"
diff --git a/Cargo.toml b/Cargo.toml
index 2be2d18..39c7286 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,5 +1,5 @@
 [package]
-name = "doom"
+name = "dungeon"
 version = "0.1.0"
 edition = "2024"
 
diff --git a/src/game.rs b/src/game.rs
index 1c13dd4..a739f6d 100644
--- a/src/game.rs
+++ b/src/game.rs
@@ -694,6 +694,9 @@ pub struct Game {
 
     // ---- death screen ----
     pub death_frames: u32,
+
+    // ---- horror effects ----
+    frame_counter: u64,
 }
 
 fn smoothstep(t: f64) -> f64 {
@@ -748,6 +751,7 @@ impl Game {
             flash_alpha: 0.0,
             show_controls: true,
             death_frames: 0,
+            frame_counter: 0,
         }
     }
 
@@ -762,6 +766,8 @@ impl Game {
     /// Returns true when the current animation phase finishes and we should
     /// advance the state machine.
     pub fn update_animation(&mut self, dt: f64) -> bool {
+        self.frame_counter = self.frame_counter.wrapping_add(1);
+
         // Flash always fades, regardless of state.
         if self.flash_alpha > 0.0 {
             self.flash_alpha = (self.flash_alpha - dt * 4.0).max(0.0);
@@ -1016,6 +1022,9 @@ impl Game {
                     self.maze.take_entity(fx, fy);
                     self.kills += 1;
                     self.set_message(&format!("You slay the enemy! ({} dmg)", total_dmg));
+                    self.flash_color = 0xFF_CC3333;
+                    self.flash_alpha = 0.4;
+                    self.begin_attack_animation();
                 } else {
                     self.maze.entity_at_mut(fx, fy).map(|e| {
                         if let Entity::Enemy { hp: h, .. } = e {
@@ -1030,16 +1039,17 @@ impl Game {
                     ));
                     if self.hp == 0 {
                         self.state = GameState::GameOver;
+                    } else {
+                        self.flash_color = 0xFF_CC3333;
+                        self.flash_alpha = 0.4;
+                        self.begin_attack_animation();
                     }
                 }
-                self.flash_color = 0xFF_CC3333;
-                self.flash_alpha = 0.4;
-                self.begin_attack_animation();
                 true
             }
 
             Some(Entity::Hallucination { persistent, hp }) => {
-                self.sanity = self.sanity.saturating_sub(10);
+                self.sanity = self.sanity.saturating_sub(30);
                 let new_hp = hp.saturating_sub(1);
 
                 if !persistent || new_hp == 0 {
@@ -1224,7 +1234,8 @@ impl Game {
         // Clear acted-this-turn tracking (enemy AI already consumed it).
         self.acted_this_turn.clear();
 
-        // Weakness grows every 3 turns, not every turn.
+        // At sanity < 20%, hallucinations become persistent with extra HP.
+        self.upgrade_hallucinations();
         if self.heartbeat_count % 3 == 0 {
             self.weakness = (self.weakness + 1).min(MAX_WEAKNESS);
         }
@@ -1244,6 +1255,9 @@ impl Game {
                 self.hp -= 1;
             }
         }
+
+        // Shifting maze: wall cells may flip at low sanity.
+        self.shift_maze();
     }
 
     /// Skip the player's turn (C key).  Enemies still act.
@@ -1464,12 +1478,13 @@ impl Game {
 
             // ---- hallucination behaviour gating ----
             if is_hallucination {
-                if self.sanity >= 40 {
-                    // Static: hallucinations don't move or attack.
+                if self.depth <= 3 || self.sanity >= 40 {
+                    // Depth 1-3: hallucinations always static.
+                    // Sanity >= 40%: hallucinations are static.
                     continue;
                 }
-                // Sanity 20-39%: patrol only.
-                // Sanity < 20%: chase (handled below via has_line_of_sight).
+                // Depth 4+ and sanity 20-39%: patrol only.
+                // Depth 7+ and sanity < 20%: chase (handled below via has_line_of_sight).
             }
 
             // ---- adjacent → attack ----
@@ -1505,11 +1520,11 @@ impl Game {
             let has_los = self.has_line_of_sight(ex, ey, px, py);
 
             if has_los {
-                // Real enemies always chase; hallucinations chase only at sanity < 20%.
+                // Real enemies always chase; hallucinations chase only at depth 7+ and sanity < 20%.
                 if !is_hallucination {
                     self.try_move_enemy_toward(ex, ey, &mut occupied);
                     continue;
-                } else if self.sanity < 20 {
+                } else if self.depth >= 7 && self.sanity < 20 {
                     self.try_move_enemy_toward(ex, ey, &mut occupied);
                     continue;
                 }
@@ -1608,9 +1623,216 @@ impl Game {
         self.attacking = false;
         self.enemy_moves.clear();
         self.acted_this_turn.clear();
+        self.frame_counter = 0;
         self.set_message(&format!("You descend to depth {}...", self.depth));
     }
 
+    // ---- horror effects ---------------------------------------------------
+
+    /// Phantom wall probability based on current sanity.
+    fn phantom_chance(&self) -> f64 {
+        match self.sanity {
+            80..=100 => 0.0,
+            60..=79 => 0.05,
+            40..=59 => 0.10,
+            20..=39 => 0.15,
+            _ => 0.20,
+        }
+    }
+
+    /// Simple deterministic hash for phantom effect placement.
+    fn phantom_hash(&self, x: usize, y: usize) -> u64 {
+        let h = (x as u64)
+            .wrapping_mul(0x9e3779b9)
+            .wrapping_add((y as u64).wrapping_mul(0x517cc1b727220a95))
+            .wrapping_add(self.heartbeat_count);
+        (h ^ (h >> 33)).wrapping_mul(0xc6a4a7935bd1e995)
+    }
+
+    /// True if this passage cell should render as a wall (phantom wall).
+    pub fn is_phantom_wall(&self, x: usize, y: usize) -> bool {
+        let chance = self.phantom_chance();
+        if chance <= 0.0 {
+            return false;
+        }
+        // Only applies to passages — walls are already walls.
+        if self.maze.is_wall(y, x) {
+            return false;
+        }
+        (self.phantom_hash(x, y) % 1000) < (chance * 1000.0) as u64
+    }
+
+    /// True if this wall cell should render as a passage (phantom passage).
+    pub fn is_phantom_passage(&self, x: usize, y: usize) -> bool {
+        let chance = self.phantom_chance();
+        if chance <= 0.0 {
+            return false;
+        }
+        // Only applies to walls — passages are already passages.
+        if !self.maze.is_wall(y, x) {
+            return false;
+        }
+        // Never make the cell the player is standing in a phantom passage.
+        let px = self.player.x.floor() as usize;
+        let py = self.player.y.floor() as usize;
+        if x == px && y == py {
+            return false;
+        }
+        (self.phantom_hash(x, y) % 1000) < (chance * 1000.0) as u64
+    }
+
+    /// Depth darkness factor: 0.0 at depth 1, up to 0.8 at depth 15+.
+    pub fn depth_darkness_factor(&self) -> f64 {
+        ((self.depth as f64 - 1.0).min(14.0) / 14.0) * 0.8
+    }
+
+    /// Combined darkness factor: weakness × depth, 0..2 range.
+    pub fn darkness_factor(&self) -> f64 {
+        self.weakness_factor() + self.depth_darkness_factor()
+    }
+
+    /// Sanity-based colour drift angle (radians) for hue-rotation effect.
+    pub fn color_drift(&self) -> f64 {
+        if self.sanity >= 80 {
+            return 0.0;
+        }
+        let t = (80.0 - self.sanity as f64) / 80.0; // 0..1 as sanity drops
+        let wave = (self.frame_counter as f64 * 0.02).sin() * 0.5 + 0.5;
+        t * wave * 0.08 // max ~0.08 rad hue rotation
+    }
+
+    /// Wall-breathing X offset for texture sampling (subtle wave).
+    pub fn wall_breathing(&self) -> f64 {
+        if self.sanity >= 80 {
+            return 0.0;
+        }
+        let t = (80.0 - self.sanity as f64) / 80.0;
+        (self.frame_counter as f64 * 0.03).sin() * t * 3.0 // ±3 texels at worst
+    }
+
+    /// Upgrade all hallucinations to persistent with extra HP when sanity < 20%.
+    fn upgrade_hallucinations(&mut self) {
+        if self.sanity >= 20 {
+            return;
+        }
+        for y in 0..self.maze.height() {
+            for x in 0..self.maze.width() {
+                if let Some(Entity::Hallucination { persistent, hp }) =
+                    self.maze.entity_at_mut(x, y)
+                {
+                    if !*persistent {
+                        *persistent = true;
+                        *hp = 3; // takes multiple attacks to dissipate
+                    }
+                }
+            }
+        }
+    }
+
+    /// Shifting maze: flip 1-3 random wall cells outside player FOV.
+    /// Called during turn resolution.
+    fn shift_maze(&mut self) {
+        // Depth 1–3: no shifting.
+        if self.depth <= 3 {
+            return;
+        }
+        // Chance based on sanity.
+        let chance = match self.sanity {
+            40..=59 => 0.05,
+            20..=39 => 0.10,
+            _ if self.sanity < 20 => 0.15,
+            _ => return,
+        };
+        let mut rng = rand::rng();
+        if !rng.random_bool(chance) {
+            return;
+        }
+
+        let w = self.maze.width();
+        let h = self.maze.height();
+        let px = self.player.x.floor() as isize;
+        let py = self.player.y.floor() as isize;
+        let ex = self.maze.exit_x as isize;
+        let ey = self.maze.exit_y as isize;
+
+        // Candidates: wall cells at least 6 tiles from player (Chebyshev).
+        let mut candidates: Vec<(usize, usize)> = Vec::new();
+        for y in 1..h - 1 {
+            for x in 1..w - 1 {
+                // Only wall cells, not the exit.
+                if !self.maze.is_wall(y, x) {
+                    continue;
+                }
+                if x == self.maze.exit_x && y == self.maze.exit_y {
+                    continue;
+                }
+                // At least 6 tiles away from player.
+                let dx = (x as isize - px).abs();
+                let dy = (y as isize - py).abs();
+                if dx.max(dy) < 6 {
+                    continue;
+                }
+                candidates.push((x, y));
+            }
+        }
+
+        if candidates.is_empty() {
+            return;
+        }
+
+        let flips = rng.random_range(1..=3).min(candidates.len());
+        shuffle_slice(&mut candidates, &mut rng);
+
+        for i in 0..flips {
+            let (x, y) = candidates[i];
+            // Flip wall → passage (or passage → wall, but we only collected walls).
+            let idx = y * w + x;
+            self.maze.cells[idx] = Cell::Passage;
+
+            // Validate: can the player still reach the exit?
+            if !self.path_exists((px as usize, py as usize), (ex as usize, ey as usize)) {
+                // Revert.
+                self.maze.cells[idx] = Cell::Wall;
+            }
+        }
+    }
+
+    /// BFS: is there a path of passage cells from `from` to `to`?
+    fn path_exists(&self, from: (usize, usize), to: (usize, usize)) -> bool {
+        let w = self.maze.width();
+        let h = self.maze.height();
+        let mut visited = vec![false; w * h];
+        let mut queue = std::collections::VecDeque::new();
+        queue.push_back(from);
+        visited[from.1 * w + from.0] = true;
+
+        let dirs: [(isize, isize); 4] = [(1, 0), (-1, 0), (0, 1), (0, -1)];
+
+        while let Some((cx, cy)) = queue.pop_front() {
+            if cx == to.0 && cy == to.1 {
+                return true;
+            }
+            for (dx, dy) in dirs {
+                let nx = cx as isize + dx;
+                let ny = cy as isize + dy;
+                if nx < 0 || ny < 0 || nx >= w as isize || ny >= h as isize {
+                    continue;
+                }
+                let nx = nx as usize;
+                let ny = ny as usize;
+                if visited[ny * w + nx] {
+                    continue;
+                }
+                if self.maze.is_wall(ny, nx) {
+                    continue;
+                }
+                visited[ny * w + nx] = true;
+                queue.push_back((nx, ny));
+            }
+        }
+        false
+    }
+
     /// Whole heartbeats elapsed (displayed in HUD).
     pub fn heartbeats(&self) -> usize {
         self.heartbeat_count as usize
diff --git a/src/renderer.rs b/src/renderer.rs
index 885e5de..86862f0 100644
--- a/src/renderer.rs
+++ b/src/renderer.rs
@@ -108,6 +108,8 @@ impl Renderer {
 
         let half_h = self.screen_h as f64 / 2.0;
         let fov = std::f64::consts::PI / 3.0;
+        let drift = game.color_drift();
+        let breathing = game.wall_breathing();
 
         // Per-column wall distances for entity occlusion.
         // Store Euclidean (for occlusion) and perp (for rendering).
@@ -173,7 +175,18 @@ impl Renderer {
                     break;
                 }
 
-                if game.maze.is_wall(map_y as usize, map_x as usize) {
+                let ux = map_x as usize;
+                let uy = map_y as usize;
+
+                // Phantom passage: a wall that appears as a passage.
+                // Skip it — the ray passes through.
+                if game.maze.is_wall(uy, ux) && game.is_phantom_passage(ux, uy) {
+                    continue;
+                }
+
+                // Phantom wall: a passage that appears as a wall.
+                // OR a real wall.  Either way, stop the ray here.
+                if game.maze.is_wall(uy, ux) || game.is_phantom_wall(ux, uy) {
                     euclidean = if !hit_side {
                         (map_x as f64 - game.player.x + (1.0 - step_x as f64) / 2.0) / rdx
                     } else {
@@ -198,11 +211,13 @@ impl Renderer {
                 game.player.x + euclidean * rdx
             };
             let wall_x = wall_x - wall_x.floor();
-            let tex_x = ((wall_x * TEX_SIZE as f64) as usize).min(TEX_SIZE - 1);
+            // Wall breathing: subtle horizontal texture wobble.
+            let tex_x = (((wall_x + breathing / TEX_SIZE as f64) * TEX_SIZE as f64) as isize)
+                .rem_euclid(TEX_SIZE as isize) as usize;
 
             let wall_bright_fx = {
-                let w = game.weakness_factor();
-                let darken_scale = 1.0 + w * 12.0;
+                let d = game.darkness_factor();
+                let darken_scale = 1.0 + d * 12.0;
                 let b = 1.0 / (1.0 + perp_dist * 0.25 * darken_scale);
                 (b * 256.0) as u32
             };
@@ -212,13 +227,14 @@ impl Renderer {
                     / wall_h as f64) as usize;
                 let tex_y = tex_y.min(TEX_SIZE - 1);
                 let color = game.wall_texture[tex_y * TEX_SIZE + tex_x];
-                buffer[py * self.screen_w + sx] = darken_fx(color, wall_bright_fx);
+                buffer[py * self.screen_w + sx] =
+                    color_drift_fx(darken_fx(color, wall_bright_fx), drift);
             }
 
             let floor_start = draw_end + 1;
             if floor_start < self.screen_h {
-                let w = game.weakness_factor();
-                let darken_scale = 1.0 + w * 12.0;
+                let d = game.darkness_factor();
+                let darken_scale = 1.0 + d * 12.0;
                 for py in floor_start..self.screen_h {
                     let floor_dist = self.floor_dist_lut[py];
                     let bright = 1.0 / (1.0 + floor_dist * 0.35 * darken_scale);
@@ -226,7 +242,7 @@ impl Renderer {
 
                     if floor_dist > 15.0 {
                         let gray = darken_fx(0xFF80_8080, bright_fx);
-                        buffer[py * self.screen_w + sx] = gray;
+                        buffer[py * self.screen_w + sx] = color_drift_fx(gray, drift);
                     } else {
                         let fx = game.player.x + floor_dist * rdx_floor;
                         let fy = game.player.y + floor_dist * rdy_floor;
@@ -238,7 +254,8 @@ impl Renderer {
                             } else {
                                 game.floor_texture[fty * TEX_SIZE + ftx]
                             };
-                        buffer[py * self.screen_w + sx] = darken_fx(color, bright_fx);
+                        buffer[py * self.screen_w + sx] =
+                            color_drift_fx(darken_fx(color, bright_fx), drift);
                     }
                 }
             }
@@ -352,7 +369,8 @@ impl Renderer {
                 s.scale,
                 s.color,
                 s.cam_z,
-                game.weakness_factor(),
+                game.darkness_factor(),
+                game.color_drift(),
                 wall_euclidean,
             );
         }
@@ -418,6 +436,7 @@ impl Renderer {
         color: u32,
         cam_z: f64,
         weakness: f64,
+        drift: f64,
         wall_euclidean: &[f64],
     ) {
         let glyph = match find_glyph(ch) {
@@ -428,7 +447,7 @@ impl Renderer {
         let darken_scale = 1.0 + weakness * 12.0;
         let bright = 1.0 / (1.0 + cam_z * 0.15 * darken_scale);
         let bright_fx = (bright * 256.0) as u32;
-        let final_color = darken_fx(color, bright_fx);
+        let final_color = color_drift_fx(darken_fx(color, bright_fx), drift);
 
         let draw_w = (LETTER_W as f64 * scale) as isize;
         let draw_h = (LETTER_H as f64 * scale) as isize;
@@ -707,3 +726,33 @@ fn darken_fx(color: u32, bright_fx: u32) -> u32 {
     let b = ((color & 0xFF) * bright_fx) >> 8;
     0xFF00_0000 | (r << 16) | (g << 8) | b
 }
+
+/// Subtle hue rotation for sanity-based colour drift.
+/// `drift` is a small angle in radians; 0 means no change.
+fn color_drift_fx(color: u32, drift: f64) -> u32 {
+    if drift.abs() < 0.001 {
+        return color;
+    }
+    let r = ((color >> 16) & 0xFF) as f64 / 255.0;
+    let g = ((color >> 8) & 0xFF) as f64 / 255.0;
+    let b = (color & 0xFF) as f64 / 255.0;
+
+    // Cheap hue shift: rotate in RGB space around the gray axis.
+    let gray = (r + g + b) / 3.0;
+    let dr = r - gray;
+    let dg = g - gray;
+    let db = b - gray;
+
+    let cos_d = drift.cos();
+    let sin_d = drift.sin();
+
+    // Rotate the RG plane (simple 2D projection for subtle effect).
+    let nr = gray + dr * cos_d - dg * sin_d * 0.5 + db * sin_d * 0.3;
+    let ng = gray + dg * cos_d + dr * sin_d * 0.5 - db * sin_d * 0.3;
+    let nb = gray + db * cos_d - dr * sin_d * 0.3 + dg * sin_d * 0.3;
+
+    let r = (nr.clamp(0.0, 1.0) * 255.0) as u32;
+    let g = (ng.clamp(0.0, 1.0) * 255.0) as u32;
+    let b = (nb.clamp(0.0, 1.0) * 255.0) as u32;
+    0xFF00_0000 | (r << 16) | (g << 8) | b
+}