Let enemies break tank collision stalemates

src/game.js

@@ -213,6 +213,7 @@
       team,
       fireTimer: 0,
       aiTimer: 0.4 + Math.random() * 1.2,
+      avoidTimer: 0,
       alive: true,
     };
   }
@@ -347,9 +348,10 @@
     const livingEnemies = enemies.filter((enemy) => enemy.alive);
     for (const enemy of livingEnemies) {
       enemy.fireTimer = Math.max(0, enemy.fireTimer - dt);
+      enemy.avoidTimer = Math.max(0, enemy.avoidTimer - dt);
       enemy.aiTimer -= dt;
 
-      if (enemy.aiTimer <= 0) {
+      if (enemy.aiTimer <= 0 && enemy.avoidTimer <= 0) {
         enemy.dir = chooseEnemyDirection(enemy);
         enemy.aiTimer = 0.45 + Math.random() * 1.25;
       }
@@ -357,12 +359,16 @@
       const dir = DIRS[enemy.dir];
       const moved = moveTank(enemy, dir.x * ENEMY_SPEED * dt, dir.y * ENEMY_SPEED * dt, livingEnemies);
       if (!moved) {
-        enemy.dir = randomDirection();
-        enemy.aiTimer = 0.25;
+        const escapeDir = chooseOpenEnemyDirection(enemy, livingEnemies);
+        enemy.dir = escapeDir || randomDirection();
+        enemy.avoidTimer = 0.55;
+        enemy.aiTimer = 0.2;
+        const next = DIRS[enemy.dir];
+        moveTank(enemy, next.x * ENEMY_SPEED * dt, next.y * ENEMY_SPEED * dt, livingEnemies);
       }
 
       if (canSeePlayer(enemy) || Math.random() < dt * 0.18) {
-        facePlayer(enemy);
+        if (enemy.avoidTimer <= 0) facePlayer(enemy);
         fire(enemy);
       }
     }
@@ -383,6 +389,35 @@
     return names[Math.floor(Math.random() * names.length)];
   }
 
+  function chooseOpenEnemyDirection(enemy, livingEnemies) {
+    const preferred = shuffledDirections().sort((a, b) => distanceFromPlayer(enemy, b) - distanceFromPlayer(enemy, a));
+    return preferred.find((name) => canMove(enemy, name, livingEnemies));
+  }
+
+  function shuffledDirections() {
+    const names = Object.keys(DIRS);
+    for (let i = names.length - 1; i > 0; i -= 1) {
+      const j = Math.floor(Math.random() * (i + 1));
+      [names[i], names[j]] = [names[j], names[i]];
+    }
+    return names;
+  }
+
+  function distanceFromPlayer(enemy, dirName) {
+    const dir = DIRS[dirName];
+    const nextX = enemy.x + dir.x * TILE;
+    const nextY = enemy.y + dir.y * TILE;
+    const dx = nextX - player.x;
+    const dy = nextY - player.y;
+    return dx * dx + dy * dy;
+  }
+
+  function canMove(entity, dirName, peerEnemies) {
+    const dir = DIRS[dirName];
+    const probe = { ...entity, x: entity.x + dir.x * 4, y: entity.y + dir.y * 4 };
+    return !isBlocked(probe, peerEnemies.filter((peer) => peer !== entity));
+  }
+
   function facePlayer(enemy) {
     const dx = player.x - enemy.x;
     const dy = player.y - enemy.y;