Fix: Standardize MIRV travel time

Addresses player report regarding unfair and unintuitive MIRV launch delays.
MIRV travel time is now fixed at 5 ticks, independent of click location.

- Modified MIRVExecution.ts to dynamically calculate speed based on a fixed travel time.
- Added MIRVExecution.test.ts to verify the fixed travel time.

src/core/execution/MIRVExecution.ts

@@ -22,6 +22,7 @@ export class MirvExecution implements Execution {
 
   private mirvRange = 1500;
   private warheadCount = 350;
+  private MIRV_FIXED_TRAVEL_TIME = 5; // Ticks
 
   private random: PseudoRandom;
 
@@ -43,7 +44,7 @@ export class MirvExecution implements Execution {
     this.mg = mg;
     this.pathFinder = new ParabolaPathFinder(mg);
     this.targetPlayer = this.mg.owner(this.dst);
-    this.speed = this.mg.config().defaultNukeSpeed();
+
 
     // Record stats
     this.mg.stats().bombLaunch(this.player, this.targetPlayer, UnitType.MIRV);
@@ -75,6 +76,9 @@ export class MirvExecution implements Execution {
       const y = Math.max(0, this.mg.y(this.dst) - 500) + 50;
       this.separateDst = this.mg.ref(x, y);
       this.pathFinder.computeControlPoints(spawn, this.separateDst);
+      // Calculate speed for fixed travel time
+      const distance = this.mg.euclideanDist(spawn, this.separateDst);
+      this.speed = distance / this.MIRV_FIXED_TRAVEL_TIME;
 
       this.mg.displayIncomingUnit(
         this.nuke.id(),

tests/core/executions/MIRVExecution.test.ts

@@ -0,0 +1,69 @@
+import { MirvExecution } from "../../../src/core/execution/MIRVExecution";
+import { SpawnExecution } from "../../../src/core/execution/SpawnExecution";
+import {
+  Game,
+  Player,
+  PlayerInfo,
+  PlayerType,
+  UnitType,
+} from "../../../src/core/game/Game";
+import { TileRef } from "../../../src/core/game/GameMap";
+import { setup } from "../../util/Setup";
+import { constructionExecution, executeTicks } from "../../util/utils";
+
+let game: Game;
+let player: Player;
+
+describe("MirvExecution", () => {
+  beforeEach(async () => {
+    game = await setup("plains", { infiniteGold: true, instantBuild: true });
+    const playerInfo = new PlayerInfo(
+      "player_id",
+      PlayerType.Human,
+      null,
+      "player_id",
+    );
+    game.addPlayer(playerInfo);
+
+    game.addExecution(
+      new SpawnExecution(game.player(playerInfo.id).info(), game.ref(1, 1)),
+    );
+
+    while (game.inSpawnPhase()) {
+      game.executeNextTick();
+    }
+
+    player = game.player("player_id");
+
+    constructionExecution(game, player, 1, 1, UnitType.MissileSilo);
+  });
+
+  test("MIRV should have a fixed travel time regardless of target distance", async () => {
+    const nearTarget = game.ref(5, 5);
+    const farTarget = game.ref(50, 50);
+
+    const mirvNear = new MirvExecution(player, nearTarget);
+    game.addExecution(mirvNear);
+    const mirvFar = new MirvExecution(player, farTarget);
+    game.addExecution(mirvFar);
+
+    // Execute ticks until both MIRVs have landed
+    let ticksNear = 0;
+    let ticksFar = 0;
+
+    while (mirvNear.isActive() || mirvFar.isActive()) {
+      game.executeNextTick();
+      if (mirvNear.isActive()) {
+        ticksNear++;
+      }
+      if (mirvFar.isActive()) {
+        ticksFar++;
+      }
+    }
+
+    // The travel times should be approximately the same
+    // Allowing for a small margin of error due to pathfinding or tick execution nuances
+    const tolerance = 2; // Ticks
+    expect(Math.abs(ticksNear - ticksFar)).toBeLessThanOrEqual(tolerance);
+  });
+});