Post-Game Content:
* The Kanto Region: You gain the ability to travel to Kanto through the Kanto Safari Zone. You can then challenge the Kanto Elite Four and Champion, Lance!
* New Pokemon: You can catch Kanto region Pokemon that weren't available in Johto, such as Eevee, Pikachu, and even some legendary Pokemon.
* Side Quests:
* New Island: An island with new Pokemon and challenges appears after you beat the Elite Four.
* Events: You can encounter special events like the Celebi event and the Mewtwo event.
* The Bug Catching Contest: You can compete in this contest to win prizes.
* The Pokeathlon Dome: Put your Pokemon through their paces in this exciting competition.
* Trainer Encounters: You can encounter new trainers who have powerful Pokemon, testing your skills.
* The Battle Frontier: After you beat the Kanto Elite Four, you can enter the Battle Frontier, a series of challenging facilities, each with its own unique rules.
* Raising Your Pokemon: With the post-game content, you'll have even more opportunities to raise your Pokemon to their full potential.
Other Post-Game Activities:
* Catching all the Pokemon: You can try to complete your Pokedex and catch all the Pokemon available in the game.
* Training and Breeding: You can further train and breed your Pokemon to create powerful teams.
* Replaying the Game: You can replay the game at a higher difficulty level for a new challenge.
HeartGold is a truly open-ended game after you beat the Elite Four, providing you with hours of fun and opportunities to further explore the world and challenge yourself.