Some little HumansVsNations improvements before public games launch 🤖 (#2825)

## Description:

- Added `generateUniqueNationName()` to `NationCreation` because I saw a
duplicate name while spawning 300 nations on Pangaea 😄
- Switched HumansVsNations public game difficulty from hard to
impossible because I realized how crazy strong troop donations between
humans are (in an enzo HVN stream).

Maybe I have to make nations donate troops to each other, we will see...
Playtests won't tell the truth because the players attending these are
probably better than the usual OF player. I will try to check the HVN
winrate via API after launch

## Please complete the following:

- [X] I have added screenshots for all UI updates
- [X] I process any text displayed to the user through translateText()
and I've added it to the en.json file
- [X] I have added relevant tests to the test directory
- [X] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced

## Please put your Discord username so you can be contacted if a bug or
regression is found:

FloPinguin

src/core/game/NationCreation.ts

@@ -69,9 +69,11 @@ export function createNationsForGame(
 
   // If we need more nations than defined in manifest, create additional ones
   const nations: Nation[] = manifestNations.map(toNation);
+  const usedNames = new Set(nations.map((n) => n.playerInfo.name));
   const additionalCount = targetNationCount - manifestNations.length;
   for (let i = 0; i < additionalCount; i++) {
-    const name = generateNationName(random);
+    const name = generateUniqueNationName(random, usedNames);
+    usedNames.add(name);
     nations.push(
       new Nation(
         undefined,
@@ -97,6 +99,45 @@ export function getCompactMapNationCount(
   return manifestNationCount;
 }
 
+function generateUniqueNationName(
+  random: PseudoRandom,
+  usedNames: Set<string>,
+): string {
+  for (let attempt = 0; attempt < 1000; attempt++) {
+    const name = generateNationName(random);
+    if (!usedNames.has(name)) {
+      return name;
+    }
+  }
+  // Fallback if we can't generate unique name (extremely unlikely)
+  // Append a number to ensure uniqueness
+  let counter = 1;
+  const baseName = generateNationName(random);
+  while (usedNames.has(`${baseName} ${counter}`)) {
+    counter++;
+  }
+  return `${baseName} ${counter}`;
+}
+
+function generateNationName(random: PseudoRandom): string {
+  const template = NAME_TEMPLATES[random.nextInt(0, NAME_TEMPLATES.length)];
+  const noun = NOUNS[random.nextInt(0, NOUNS.length)];
+
+  const result: string[] = [];
+
+  for (const part of template) {
+    if (part === PLURAL_NOUN) {
+      result.push(pluralize(noun));
+    } else if (part === NOUN) {
+      result.push(noun);
+    } else {
+      result.push(part);
+    }
+  }
+
+  return result.join(" ");
+}
+
 const PLURAL_NOUN = Symbol("plural!");
 const NOUN = Symbol("noun!");
 
@@ -290,25 +331,6 @@ const NOUNS = [
   "Penguin",
 ];
 
-function generateNationName(random: PseudoRandom): string {
-  const template = NAME_TEMPLATES[random.nextInt(0, NAME_TEMPLATES.length)];
-  const noun = NOUNS[random.nextInt(0, NOUNS.length)];
-
-  const result: string[] = [];
-
-  for (const part of template) {
-    if (part === PLURAL_NOUN) {
-      result.push(pluralize(noun));
-    } else if (part === NOUN) {
-      result.push(noun);
-    } else {
-      result.push(part);
-    }
-  }
-
-  return result.join(" ");
-}
-
 // Words from NOUNS that need irregular "-oes" plural
 const O_TO_OES = new Set(["Potato", "Tomato"]);
 

src/server/MapPlaylist.ts

@@ -121,7 +121,9 @@ export class MapPlaylist {
       gameMapSize: isCompact ? GameMapSize.Compact : GameMapSize.Normal,
       publicGameModifiers: { isCompact, isRandomSpawn },
       difficulty:
-        playerTeams === HumansVsNations ? Difficulty.Hard : Difficulty.Easy,
+        playerTeams === HumansVsNations
+          ? Difficulty.Impossible
+          : Difficulty.Easy,
       infiniteGold: false,
       infiniteTroops: false,
       maxTimerValue: undefined,