This is not a fan-made mod or a weird game edit. It is just the real game in digital form.

In the context of retro gaming and ROMs, "Xenophobia" refers to the scene release group that originally dumped and uploaded the game files to the internet, rather than being a specific gameplay modification or "ROM hack". Pokemon HeartGold (U)(Xenophobia) typically denotes the

The original retail game included a physical pedometer that let you walk your Pokémon in real life to earn EXP and find items. Modern Ways to Experience HeartGold