diff --git a/assets/images/civilization/civilization-cities-japanese.png b/assets/images/civilization/civilization-cities-japanese.png
new file mode 100644
index 0000000..47d73da
Binary files /dev/null and b/assets/images/civilization/civilization-cities-japanese.png differ
diff --git a/assets/images/civilization/civilization-cities-japanese.psd b/assets/images/civilization/civilization-cities-japanese.psd
new file mode 100644
index 0000000..a5aac5c
Binary files /dev/null and b/assets/images/civilization/civilization-cities-japanese.psd differ
diff --git a/data/civilization-artwork.json b/data/civilization-artwork.json
index 7d4d442..93e0a0e 100644
--- a/data/civilization-artwork.json
+++ b/data/civilization-artwork.json
@@ -15,6 +15,7 @@
   "iconSheet": { "key": "civilization-icons", "path": null, "frameWidth": 48, "frameHeight": 48 },
   "citySheets": {
     "classic": { "key": "civilization-cities-classic", "path": "assets/images/civilization/civilization-cities-classic.png", "frameWidth": 128, "frameHeight": 96 },
-    "cyberpunk": { "key": "civilization-cities-cyberpunk", "path": "assets/images/civilization/civilization-cities-cyberpunk.png", "frameWidth": 128, "frameHeight": 96 }
+    "cyberpunk": { "key": "civilization-cities-cyberpunk", "path": "assets/images/civilization/civilization-cities-cyberpunk.png", "frameWidth": 128, "frameHeight": 96 },
+    "japanese": { "key": "civilization-cities-japanese", "path": "assets/images/civilization/civilization-cities-japanese.png", "frameWidth": 128, "frameHeight": 96 }
   }
 }
diff --git a/data/opponents.json b/data/opponents.json
index 18a7f9f..47a7cba 100644
--- a/data/opponents.json
+++ b/data/opponents.json
@@ -9,7 +9,7 @@
         "alphabet",
         "pottery"
       ],
-      "citySheet": "classic",
+      "citySheet": "cyberpunk",
       "bio": "AI Bro sent from the future to show the superiority of the future.",
       "voice": "Legion",
       "convo": [
@@ -898,7 +898,7 @@
         "masonry",
         "pottery"
       ],
-      "citySheet": "classic",
+      "citySheet": "japanese",
       "bio": "I have traveled far to play these games. Honor me and let us play!",
       "speech": {
         "intro": [
@@ -1045,7 +1045,7 @@
         "pottery",
         "thewheel"
       ],
-      "citySheet": "classic",
+      "citySheet": "japanese",
       "bio": "From a different galaxy, but has the same great Earth based lifeforms taste for games!",
       "speech": {
         "intro": [
@@ -1080,7 +1080,7 @@
         "horsebackriding",
         "thewheel"
       ],
-      "citySheet": "cyberpunk",
+      "citySheet": "japanese",
       "bio": "MISSION OBJECTIVE: Victory.... all other priorities recinded.",
       "speech": {
         "intro": [
diff --git a/data/tetrisattack.json b/data/tetrisattack.json
index a363d80..4fe1316 100644
--- a/data/tetrisattack.json
+++ b/data/tetrisattack.json
@@ -18,9 +18,11 @@
         "startRows": 6,
         "clearLineRows": 3,
         "introLines": [
-          "Well hey there, sugar! Ain't you a sight for sore eyes.",
+          "Well hey there, stranger! Ain't you a sight for sore eyes.",
           "These panels are stackin' up faster than I can sort 'em, and I've been at it all mornin'.",
-          "Lend me a hand and we'll have this cleared by supper."
+          "Use your arrow keys to move your selecter aroung, and press space, x, or z o swap tiles.",
+          "Get three in a row and they'll get out of town faster than a varmit at sundown!",
+          "Clear enough of 'em and you can help me clean this here town up!"
         ],
         "winLines": [
           "Well shoot, you cleared the whole mess! Bless your heart.",
diff --git a/src/games/civilization/CivilizationGame.js b/src/games/civilization/CivilizationGame.js
index af1701d..4e2839c 100644
--- a/src/games/civilization/CivilizationGame.js
+++ b/src/games/civilization/CivilizationGame.js
@@ -1224,7 +1224,10 @@ export default class CivilizationGame extends Phaser.Scene {
   afterAction() {
     // Repaint tiles that may have changed (work orders complete on turn start,
     // but roads from engineers etc. show up next refresh — cheap full check
-    // is unnecessary; unit/city layer + HUD is enough here).
+    // is unnecessary; unit/city layer + HUD is enough here). Baked-terrain
+    // features the human changes mid-turn (popping a hut) do need it now,
+    // though — waiting for startHumanTurn leaves a stale badge all turn.
+    this.repaintFromEvents();
     this.view.refresh();
     this.refreshHud();
     if (this.state.over) this.onGameOver();
@@ -1373,7 +1376,9 @@ export default class CivilizationGame extends Phaser.Scene {
     for (const e of this.state.events) {
       if (e.painted) continue;
       e.painted = true;
-      if (e.type === 'workDone') {
+      if (e.type === 'workDone' || e.type === 'hut') {
+        // A popped hut is cleared from world.huts, but the hut badge lives in
+        // the baked terrain texture — without this it stays drawn all session.
         this.view.repaintTileAndNeighbors(e.x, e.y);
       } else if (e.type === 'cityFounded' || e.type === 'cityDestroyed') {
         const city = Logic.cityById(this.state, e.cityId);
diff --git a/src/games/civilization/CivilizationLogic.js b/src/games/civilization/CivilizationLogic.js
index 424e78f..3190311 100644
--- a/src/games/civilization/CivilizationLogic.js
+++ b/src/games/civilization/CivilizationLogic.js
@@ -899,11 +899,14 @@ export function disembarkTiles(rules, state, boat) {
 
 function resolveHut(rules, state, unit) {
   const civ = state.civs[unit.civ];
+  // Captured up front: the hut tile is what the view has to repaint, and an
+  // ambush loss removes the unit before the event is pushed.
+  const { x, y } = unit;
   const roll = rand(state);
   if (roll < 0.4) {
     const gold = 25 * (1 + randInt(state, 4));
     civ.gold += gold;
-    state.events.push({ type: 'hut', civ: civ.id, outcome: 'gold', gold });
+    state.events.push({ type: 'hut', civ: civ.id, outcome: 'gold', gold, x, y });
     return { outcome: 'gold', gold };
   }
   if (roll < 0.65) {
@@ -911,17 +914,17 @@ function resolveHut(rules, state, unit) {
     if (options.length) {
       const tech = options[randInt(state, options.length)];
       grantTech(rules, state, civ, tech.id);
-      state.events.push({ type: 'hut', civ: civ.id, outcome: 'tech', tech: tech.id });
+      state.events.push({ type: 'hut', civ: civ.id, outcome: 'tech', tech: tech.id, x, y });
       return { outcome: 'tech', tech: tech.id };
     }
     civ.gold += 50;
-    state.events.push({ type: 'hut', civ: civ.id, outcome: 'gold', gold: 50 });
+    state.events.push({ type: 'hut', civ: civ.id, outcome: 'gold', gold: 50, x, y });
     return { outcome: 'gold', gold: 50 };
   }
   if (roll < 0.85) {
     const type = civ.known.chivalry ? 'knights' : (civ.known.ironworking ? 'legion' : 'horsemen');
     spawnUnit(rules, state, unit.civ, type, unit.x, unit.y, null);
-    state.events.push({ type: 'hut', civ: civ.id, outcome: 'unit', unit: type });
+    state.events.push({ type: 'hut', civ: civ.id, outcome: 'unit', unit: type, x, y });
     return { outcome: 'unit', unit: type };
   }
   // Ambush: fight a phantom era-scaled hostile on the spot.
@@ -932,11 +935,11 @@ function resolveHut(rules, state, unit) {
     phantom.defense, phantom.hp, phantom.fp, unit.hp);
   if (!survived.attackerWon) {
     removeUnit(state, unit);
-    state.events.push({ type: 'hut', civ: civ.id, outcome: 'ambushLost' });
+    state.events.push({ type: 'hut', civ: civ.id, outcome: 'ambushLost', x, y });
     return { outcome: 'ambushLost' };
   }
   unit.hp = survived.attackerHp;
-  state.events.push({ type: 'hut', civ: civ.id, outcome: 'ambushWon' });
+  state.events.push({ type: 'hut', civ: civ.id, outcome: 'ambushWon', x, y });
   return { outcome: 'ambushWon' };
 }
 
diff --git a/src/games/civilization/CivilizationWorldGen.js b/src/games/civilization/CivilizationWorldGen.js
index b9051b5..204403f 100644
--- a/src/games/civilization/CivilizationWorldGen.js
+++ b/src/games/civilization/CivilizationWorldGen.js
@@ -4,8 +4,8 @@
 // east-west wrap). Terrain from layered value noise: elevation picks land/sea
 // (exact land fraction via percentile threshold), a ridged channel places
 // hills/mountains, latitude bands place tundra/glacier/desert, and a moisture
-// channel places forest/jungle/swamp. Specials sit on a Civ II-style diagonal
-// lattice; huts scatter on land away from starting positions.
+// channel places forest/jungle/swamp. Specials sit on a jittered grid (fixed
+// density, hashed position per block); huts scatter on land away from starts.
 
 export function mulberry32(seed) {
   let a = seed >>> 0;
@@ -50,12 +50,74 @@ function makeNoise(rng, cols, rows, octaves = 3, baseFreq = 5) {
   };
 }
 
-// Civ II-ish deterministic lattices (independent of RNG so they look "placed").
-export function shieldGrassAt(x, y) { return ((x * 2 + y) % 4) < 2; }
-function specialSlotAt(x, y, offset) {
-  return ((x * 3 + y * 5 + offset) % 16) === 0;
+// 32-bit avalanche hash. Deterministic and order-independent, so tile features
+// can be decided per-coordinate without consuming the RNG stream.
+function hash3(a, b, c) {
+  let h = Math.imul(a | 0, 0x27d4eb2d) ^ Math.imul(b | 0, 0x165667b1) ^ Math.imul(c | 0, 0x9e3779b1);
+  h = Math.imul(h ^ (h >>> 15), 0x2c1b3c6d);
+  h = Math.imul(h ^ (h >>> 12), 0x297a2d39);
+  return (h ^ (h >>> 15)) >>> 0;
+}
+
+// Shield grassland: exactly 50% of tiles, stratified into 2x2 blocks.
+//
+// The old `(x*2+y) % 4 < 2` lattice repeats along a fixed grid direction, which
+// the isometric projection turns into visible screen-space banding. Plain white
+// noise removes the banding but is a balance change, not just a cosmetic one:
+// it holds the *mean* at 50% while adding per-city variance, and city growth is
+// convex, so a city that happens to draw shield-heavy tiles snowballs. In the
+// self-play soak that produced runaway empires and tripled AI turn time.
+//
+// Giving every aligned 2x2 block exactly two shield tiles — choosing which two
+// by hash — keeps a city radius near 50% the way the old lattice did, while the
+// per-block choice leaves no directional structure to read as stripes.
+//
+// Baked into a mask at load so tileYield(), which hits this for every grassland
+// tile of every city every turn, pays only a masked array read.
+// 128 exceeds the largest world (72x56), so the wrap is never visible in play.
+const SHIELD_MASK_BITS = 7;
+const SHIELD_MASK_SIZE = 1 << SHIELD_MASK_BITS;
+const BALANCED_2X2 = [
+  [1, 1, 0, 0], [1, 0, 1, 0], [1, 0, 0, 1],
+  [0, 1, 1, 0], [0, 1, 0, 1], [0, 0, 1, 1],
+];
+const SHIELD_MASK = (() => {
+  const mask = new Uint8Array(SHIELD_MASK_SIZE * SHIELD_MASK_SIZE);
+  for (let by = 0; by < SHIELD_MASK_SIZE / 2; by += 1) {
+    for (let bx = 0; bx < SHIELD_MASK_SIZE / 2; bx += 1) {
+      const pattern = BALANCED_2X2[hash3(bx, by, 0x5e1d) % BALANCED_2X2.length];
+      for (let dy = 0; dy < 2; dy += 1) {
+        for (let dx = 0; dx < 2; dx += 1) {
+          mask[(((by * 2 + dy) << SHIELD_MASK_BITS)) + bx * 2 + dx] = pattern[dy * 2 + dx];
+        }
+      }
+    }
+  }
+  return mask;
+})();
+export function shieldGrassAt(x, y) {
+  return SHIELD_MASK[((y & (SHIELD_MASK_SIZE - 1)) << SHIELD_MASK_BITS)
+    + (x & (SHIELD_MASK_SIZE - 1))] === 0;
+}
+
+// Specials: one per SPECIAL_BLOCK² tiles, jittered inside the block. Fixed
+// density keeps regions from coming out lopsidedly rich or poor; the hashed
+// offset inside each block removes the alignment a plain lattice would show.
+const SPECIAL_BLOCK = 4;
+
+// Is any of the 8 neighbours of (x,y) already a special?
+function specialNear(special, cols, rows, x, y) {
+  for (let dy = -1; dy <= 1; dy += 1) {
+    for (let dx = -1; dx <= 1; dx += 1) {
+      if (dx === 0 && dy === 0) continue;
+      const nx = x + dx;
+      const ny = y + dy;
+      if (nx < 0 || ny < 0 || nx >= cols || ny >= rows) continue;
+      if (special[ny * cols + nx] >= 0) return true;
+    }
+  }
+  return false;
 }
-function specialPick(x, y) { return ((x >> 1) + (y >> 1)) % 2; }
 
 // Improvement bit flags stored per tile.
 export const IMP = { ROAD: 1, RAILROAD: 2, IRRIGATION: 4, FARMLAND: 8, MINE: 16, FORTRESS: 32 };
@@ -155,21 +217,45 @@ function tryGenerate(rules, cols, rows, T, rng, numCivs, seed, attempt) {
   const largest = Math.max(0, ...contSizes);
   if (landCount === 0 || largest / landCount < 0.15) return null; // reroll
 
-  // Specials on the diagonal lattice (grassland gets shield variant instead).
-  const latticeOffset = Math.floor(rng() * 16);
+  // Specials: jittered grid. One per SPECIAL_BLOCK² block, placed on a hashed
+  // pick from that block's eligible tiles (grassland gets the shield variant
+  // instead, so it is never eligible). Picking among eligible tiles rather than
+  // a fixed slot means a mostly-grassland block still seeds its few hills,
+  // instead of wasting the slot and leaving the region barren.
+  const specialSalt = (rng() * 4294967296) >>> 0;
   const special = new Array(n).fill(-1);
   const specialIndexById = {};
   rules.specialList.forEach((s, i) => { specialIndexById[s.id] = i; });
-  for (let y = 0; y < rows; y += 1) {
-    for (let x = 0; x < cols; x += 1) {
-      const i = y * cols + x;
-      const terr = rules.terrainList[terrain[i]];
-      if (terr.id === 'grassland') continue;
-      if (!specialSlotAt(x, y, latticeOffset)) continue;
-      const opts = rules.specialsByTerrain[terr.id];
-      if (!opts || !opts.length) continue;
-      const pick = opts[specialPick(x, y) % opts.length];
-      special[i] = specialIndexById[pick.id];
+  const blockCols = Math.ceil(cols / SPECIAL_BLOCK);
+  const blockRows = Math.ceil(rows / SPECIAL_BLOCK);
+  for (let by = 0; by < blockRows; by += 1) {
+    for (let bx = 0; bx < blockCols; bx += 1) {
+      const eligible = [];
+      for (let dy = 0; dy < SPECIAL_BLOCK; dy += 1) {
+        for (let dx = 0; dx < SPECIAL_BLOCK; dx += 1) {
+          const x = bx * SPECIAL_BLOCK + dx;
+          const y = by * SPECIAL_BLOCK + dy;
+          if (x >= cols || y >= rows) continue;
+          const terr = rules.terrainList[terrain[y * cols + x]];
+          if (terr.id === 'grassland') continue;
+          if (!rules.specialsByTerrain[terr.id]?.length) continue;
+          eligible.push([x, y]);
+        }
+      }
+      if (!eligible.length) continue;
+
+      // Walk candidates from a hashed start, skipping any that would sit next
+      // to an already-placed special — blocks are independent otherwise, so
+      // two can both pick against their shared border and clump.
+      const start = hash3(bx, by, specialSalt) % eligible.length;
+      for (let k = 0; k < eligible.length; k += 1) {
+        const [x, y] = eligible[(start + k) % eligible.length];
+        if (specialNear(special, cols, rows, x, y)) continue;
+        const opts = rules.specialsByTerrain[rules.terrainList[terrain[y * cols + x]].id];
+        const pick = opts[hash3(x, y, specialSalt ^ 0x5bf03635) % opts.length];
+        special[y * cols + x] = specialIndexById[pick.id];
+        break;
+      }
     }
   }
 
diff --git a/src/games/civilization/sprites.md b/src/games/civilization/sprites.md
index e5768d4..f70b267 100644
--- a/src/games/civilization/sprites.md
+++ b/src/games/civilization/sprites.md
@@ -7,10 +7,10 @@ box clusters. This document lists the optional sprite sheets you can drop in
 to replace those placeholders, with exact dimensions, layouts, and
 frame-by-frame maps.
 
-All art is wired through **`public/data/civilization-artwork.json`**. The scene
+All art is wired through **`data/civilization-artwork.json`**. The scene
 checks whether each sheet's texture is loaded; if it is, it uses your frames,
 otherwise it falls back to procedural drawing. You never need to touch code —
-just add a PNG under `public/assets/images/civilization/` and set its `path`
+just add a PNG under `assets/images/civilization/` and set its `path`
 in that JSON.
 
 Frame numbering everywhere is **row-major, 0-based**: frame 0 is top-left,
@@ -36,11 +36,11 @@ against each other with no blending in v1 (hard Civ I-style edges).
 
 | | |
 |---|---|
-| **Path** | `public/assets/images/civilization/civilization-terrain.png` |
+| **Path** | `assets/images/civilization/civilization-terrain.png` |
 | **Sheet size** | **768 × 192 px** |
 | **Frame size** | **128 × 96 px** |
 | **Layout** | 6 columns × 2 rows = 12 frames |
-| **Status** | ❌ not created — procedural diamonds render meanwhile |
+| **Status** | ✅ created and loading |
 | **JSON** | `terrainSheet` |
 
 ### Frame map
@@ -72,11 +72,11 @@ on the diamond).
 
 | | |
 |---|---|
-| **Path** | `public/assets/images/civilization/civilization-resources.png` |
+| **Path** | `assets/images/civilization/civilization-resources.png` |
 | **Sheet size** | **320 × 256 px** |
 | **Frame size** | **64 × 64 px** |
 | **Layout** | 5 columns × 4 rows = 20 frames |
-| **Status** | ❌ not created — colored dot badges render meanwhile |
+| **Status** | ✅ created and loading |
 | **JSON** | `resourceSheet` |
 
 ### Frame map
@@ -113,7 +113,7 @@ vector-drawn (they connect dynamically between tiles), so they are NOT here.
 
 | | |
 |---|---|
-| **Path** | `public/assets/images/civilization/civilization-improvements.png` |
+| **Path** | `assets/images/civilization/civilization-improvements.png` |
 | **Sheet size** | **384 × 64 px** |
 | **Frame size** | **64 × 64 px** |
 | **Layout** | 6 columns × 1 row = 6 frames |
@@ -151,11 +151,11 @@ headroom band (y = 0–32), not the diamond zone.
 
 | | |
 |---|---|
-| **Path** | `public/assets/images/civilization/civilization-units.png` |
+| **Path** | `assets/images/civilization/civilization-units.png` |
 | **Sheet size** | **512 × 672 px** |
 | **Frame size** | **64 × 96 px** |
 | **Layout** | 8 columns × 7 rows = 56 frames (51 used, 52–55 reserved) |
-| **Status** | ❌ not created — roundel + 2-letter label renders meanwhile |
+| **Status** | ✅ created and loading |
 | **JSON** | `unitSheet` |
 
 ### Frame map
@@ -196,16 +196,17 @@ Frame indexes are pinned in `data/civilization-rules.json` (`units[].frame`).
 ## 5. City sheet (classic theme) — `civilization-cities-classic.png`
 
 Cities scale with population and show walls when City Walls are built. This is
-the **classic/western** theme; more themes (e.g. `asian`) drop in later by
-adding an entry to `citySheets` in the artwork JSON — the format already
-supports it and no code changes are needed.
+the **classic/western** theme; `cyberpunk` and `japanese` sheets already ship
+alongside it, and further themes drop in by adding an entry to `citySheets`
+in the artwork JSON — the format already supports it and no code changes are
+needed. Every theme uses the same frame map below.
 
 | | |
 |---|---|
-| **Path** | `public/assets/images/civilization/civilization-cities-classic.png` |
+| **Path** | `assets/images/civilization/civilization-cities-classic.png` |
 | **Sheet size** | **512 × 192 px** |
 | **Frame size** | **128 × 96 px** (same diamond+headroom as terrain) |
-| **Status** | ❌ not created — box-cluster fallback renders meanwhile |
+| **Status** | ✅ created and loading |
 | **Layout** | 4 columns × 2 rows = 8 frames |
 | **JSON** | `citySheets.classic` |
 
@@ -233,7 +234,7 @@ Small interface icons (yields, governments, spaceship parts, moods).
 
 | | |
 |---|---|
-| **Path** | `public/assets/images/civilization/civilization-icons.png` |
+| **Path** | `assets/images/civilization/civilization-icons.png` |
 | **Sheet size** | **480 × 96 px** |
 | **Frame size** | **48 × 48 px** |
 | **Layout** | 10 columns × 2 rows = 20 frames |
@@ -263,7 +264,7 @@ Government frames match `governments[].frame` in the rules JSON (10–15).
 
 | | |
 |---|---|
-| **Path** | `public/assets/images/game-icons.png` (shared sheet) |
+| **Path** | `assets/images/game-icons.png` (shared sheet) |
 | **Sheet size** | 660 × 660 px (15 × 15 grid of 44 × 44 frames) |
 | **Frame** | **83** (row 5, col 8) |
 | **Status** | ❌ needs painting |
@@ -285,6 +286,6 @@ city. The menu shows a generic fallback until painted.
 | 6 | `civilization-icons.png` | 480×96 | Low |
 | 7 | `game-icons.png` frame 83 | 44×44 | Medium (menu presence) |
 
-After painting a sheet, set its `path` in `public/data/civilization-artwork.json`,
+After painting a sheet, set its `path` in `data/civilization-artwork.json`,
 e.g. `"path": "assets/images/civilization/civilization-terrain.png"`, and
 reload — no code changes.
diff --git a/tools/verifyCivilization.js b/tools/verifyCivilization.js
index 8a89ff8..53a00f9 100644
--- a/tools/verifyCivilization.js
+++ b/tools/verifyCivilization.js
@@ -324,11 +324,59 @@ if (RULES) {
       || RULES.terrainList[w.terrain[i]].id === 'glacier')) hutsOnLand = false;
   }
   check('huts on land (not glacier)', hutsOnLand);
-  check('shield-grass lattice ~50%', (() => {
+  check('shield-grass ~50%', (() => {
     let c = 0;
-    for (let y = 0; y < 20; y += 1) for (let x = 0; x < 20; x += 1) c += shieldGrassAt(x, y) ? 1 : 0;
-    return c === 200;
+    for (let y = 0; y < 60; y += 1) for (let x = 0; x < 60; x += 1) c += shieldGrassAt(x, y) ? 1 : 0;
+    return c > 3600 * 0.45 && c < 3600 * 0.55;
   })());
+
+  // Placement must look organic: no clumps, no barren regions, no alignment.
+  let adjacentSpecials = 0;
+  for (let y = 0; y < w.rows; y += 1) {
+    for (let x = 0; x < w.cols; x += 1) {
+      if (w.special[y * w.cols + x] < 0) continue;
+      for (const [dx, dy] of [[1, 0], [0, 1], [1, 1], [1, -1]]) {
+        const nx = x + dx;
+        const ny = y + dy;
+        if (nx < 0 || ny < 0 || nx >= w.cols || ny >= w.rows) continue;
+        if (w.special[ny * w.cols + nx] >= 0) adjacentSpecials += 1;
+      }
+    }
+  }
+  check('no two specials adjacent', adjacentSpecials === 0, `${adjacentSpecials} pairs`);
+
+  // Coarse 12x12 windows: every window with land should hold some specials, and
+  // none should hoard them. Catches both barren and over-rich regions.
+  let minWin = Infinity;
+  let maxWin = 0;
+  for (let wy = 0; wy + 12 <= w.rows; wy += 12) {
+    for (let wx = 0; wx + 12 <= w.cols; wx += 12) {
+      let c = 0;
+      for (let y = wy; y < wy + 12; y += 1) {
+        for (let x = wx; x < wx + 12; x += 1) if (w.special[y * w.cols + x] >= 0) c += 1;
+      }
+      minWin = Math.min(minWin, c);
+      maxWin = Math.max(maxWin, c);
+    }
+  }
+  check('no barren 12x12 region', minWin >= 3, `min ${minWin} per window`);
+  check('no over-rich 12x12 region', maxWin <= 14, `max ${maxWin} per window`);
+
+  // Straightness: a modular lattice puts most specials on a few screen columns
+  // (iso screen-x is proportional to x - y). Real jitter spreads them out.
+  const byScreenCol = new Map();
+  let specTotal = 0;
+  for (let y = 0; y < w.rows; y += 1) {
+    for (let x = 0; x < w.cols; x += 1) {
+      if (w.special[y * w.cols + x] < 0) continue;
+      const k = x - y;
+      byScreenCol.set(k, (byScreenCol.get(k) ?? 0) + 1);
+      specTotal += 1;
+    }
+  }
+  const worstCol = Math.max(...byScreenCol.values());
+  check('specials not aligned in screen columns', worstCol <= specTotal * 0.06,
+    `worst column holds ${worstCol}/${specTotal}`);
 }
 
 // ---------------------------------------------------------------------------