diff --git a/tools/find-id-changes.js b/tools/find-id-changes.js
new file mode 100644
index 0000000..aec3459
--- /dev/null
+++ b/tools/find-id-changes.js
@@ -0,0 +1,125 @@
+#!/usr/bin/env node
+
+import { spawnSync } from "node:child_process";
+import assert from "node:assert";
+import { mkdirSync, copyFileSync } from "node:fs";
+import path from "node:path";
+import { fileURLToPath } from "node:url";
+import process from "node:process";
+
+// Generate a list of changes to "lib/games.js" where game IDs have been changed via the git history.
+// Requires git to be installed.
+// Make sure you don't have any local un-committed changes to lib/games.js
+
+// Usage: node tools/find-id-changes.js > id-changes.json
+// Output is an array of
+// {
+//   "hash":    "git commit hash",
+//   "changes": [ ["oldid", "newid"], ... ],
+//   "removed": [ "removedid", ... ],
+//   "added":   [ "addedid", ... ]
+// }
+
+// The output can be converted to a map of { "oldid": "newid" } using a jq command:
+// cat id-changes.json | jq ".[].changes | map({ (.[0]): .[1] } ) | add" | jq -s "add"
+
+const main = async (rootDir) => {
+  // Make sure CWD is the root of the repo
+  process.chdir(rootDir);
+
+  // Get list of commits that have modified lib/games.js
+  const gitLog = spawnSync(
+    "git",
+    [
+      "log",
+      "--follow",
+      "--format=%H",
+      "--diff-filter=M",
+      "--reverse",
+      "--",
+      "lib/games.js",
+    ],
+    { encoding: "utf-8" }
+  );
+
+  // Make a directory to store files in
+  mkdirSync("game_changes", { recursive: true });
+
+  const output = [];
+
+  for (const commitHash of gitLog.stdout.split("\n")) {
+    if (commitHash.length === 0) continue;
+
+    // Checkout lib/games.js before the commit that changed it
+    assert(
+      spawnSync("git", ["checkout", `${commitHash}^1`, "--", "lib/games.js"])
+        .status === 0
+    );
+
+    // We have to copy each state of the file to its own file because node caches imports
+    const beforeName = `game_changes/${commitHash}-before.js`;
+    copyFileSync("lib/games.js", beforeName);
+
+    const before = await import(path.join("../", beforeName));
+
+    // Checkout lib/games.js after the commit that changed it
+    assert(
+      spawnSync("git", ["checkout", `${commitHash}`, "--", "lib/games.js"])
+        .status === 0
+    );
+
+    const afterName = `game_changes/${commitHash}-after.js`;
+    copyFileSync("lib/games.js", afterName);
+
+    const after = await import(path.join("../", afterName));
+
+    // Find game IDs that were removed and added
+    let removed = Object.keys(before.games).filter(
+      (key) => !(key in after.games)
+    );
+    let added = Object.keys(after.games).filter(
+      (key) => !(key in before.games)
+    );
+
+    const changes = [];
+
+    for (const rm of removed) {
+      for (const add of added) {
+        const beforeGame = before.games[rm];
+        const afterGame = after.games[add];
+
+        // Modify game names to ignore case, spaces, and punctuation
+        const beforeName = beforeGame.name.toLowerCase().replace(/[^a-z]/g, "");
+        const afterName = afterGame.name.toLowerCase().replace(/[^a-z]/g, "");
+
+        if (
+          beforeGame.options.protocol === afterGame.options.protocol &&
+          (beforeName.includes(afterName) || afterName.includes(beforeName))
+        ) {
+          changes.push([rm, add]);
+          removed = removed.filter((r) => r !== rm);
+          added = added.filter((a) => a !== add);
+          break;
+        }
+      }
+    }
+
+    output.push({
+      hash: commitHash,
+      changes,
+      removed,
+      added,
+    });
+  }
+
+  // Reset the contents of lib/games.js
+  spawnSync("git", ["checkout", "--", "lib/games.js"]);
+
+  return output;
+};
+
+main(
+  // Get the root of the repo:
+  // dir of bin/find-id-changes.js -> /../
+  path.join(path.dirname(fileURLToPath(import.meta.url)), "..")
+).then((o) => console.log(JSON.stringify(o)), console.error);