Whilst being touted as effectively remakes of the old GameBoy Color games "Pokémon Gold/Silver/Crystal", HeartGold and SoulSilver really deserve to be treated as separate games in their own right; these 'remakes' add so much to the original game that, story-line aside, you are effectively playing through an entirely new experience. One that's well worth having. New features include:
* Having your Pokémon follow you around - this isn't simply a case of attaching another sprite to your own for an 'aww isn't this cute' effect. The most useful aspect is that your Pokémon will find things for you (mainly items for the Fashion Case, continued from DPPt), but also if somebody wants to see a Pokémon, you must actually show them it. This makes for a really nice 'wow, I am actually involved with my Pokémon now' feeling. Warm and fuzzy for old fans, sweet and immersive for new fans.
* The new Menu system is now entirely touch-screen based. It's a little hard to get used to, but once you do, it's very helpful. The PokéGear makes a return and is newly updated to include more use for the phone (your mother spends your money faster than you can amass it, which is handy) and annotations being able to be left on the Map, which also shows if someone has called you but you haven't collected an item/met for a re-match from them. As the phone replaces the Vs. Seeker from DPPt, this is extremely helpful.
* The PokéWalker. It's very simple: the more you walk, the more you unlock, the more you find, the more your Pokémon grows. It's not just a fancy Pedometer: it has two mini games, each costing 'Watts' which are amassed as you walk. The first (10 Watts) allows you to catch Pokémon, whilst the second (3 Watts) has you looking for items in patches of grass. Also, the more you walk, the happier your Pokémon becomes and the more likely it is to 'find' more Watts for you. When you transfer the Watts back to the DS with your Pokémon (make sure you don't spend them all!) they are counted and, when you reach some serious amounts, more Routes are unlocked for you. (Nintendo said in a recent interview with Official Nintendo Magazine that you need to walk 1,000 miles to unlock all of the Routes, so get cracking!)
* The graphics are updated from DPPt and I must say the Pokémon sprites are the best yet. Johto and Kanto look beautiful.
* The Suicune/Eusine storyline is kept from Crystal and expanded slightly, which is great! The Rockets also have some new Executives on their hands, a la Team Galactic...
* The Safari Zone has been re-introduced to Johto and is, to be frank, absolutely massive. It can be treated as a side-quest all by itself, alongside the new Pokéthlon Dome and the mini-games therein. If you're bored of the main quest and you want a break, head there for some cute fun that's better than the Contests from DPPt (in my opinion of course).
HeartGold feels the most immersive of the series so far. The characters of Rival (mine is called Silver) and Ethan/Lyra are developed, there are more side-quests than before, the 'togetherness' of humans and Pokémon hits home with all of the activities you can do, and what's even better is that the game treats you more maturely than those before and doesn't have any annoying 'let's labour the point' scenes. It's familiar, but it's not so familiar that you feel you've been there before.
So, HeartGold and SoulSilver are a must-have for both:
a) Nostalgia freaks. It's Johto, Jim, but not as we know it. It's BETTER.
b) Newcomers to the Pokémon world. Enough is explained for you to grasp what's going on, without having too much information shoved down your throat.