If you've already played Pokemon Gold, Silver or Crystal, this is virtually the same game, but upgraded in trons of new ways. Let's roll ourselves in, stock up on Poke Balls and Potions, and start our quest!
The game starts out as every Pokemon game does. You are greeted by Prof. Oak and he introduces you to the world of Pokemon. You select your gender, name and start your quest. It's the old style that everyone grew up with. I'll get to some of the new additions in a moment.
The story is what we expected. You play as the new Trainer on the block. You travel around the vast Johto region and collect your Gym Badges from each Gym, eight in total. But eventualy, something seems up, as you notice these weird uniformed men with large red R's on their shirts. No big addition to the story. A few new characters were added and Pokemon from Ruby/Sapphire/Diamond/Pearl were added after you defeat the Champion. But that's about it overall.
Ack! No! Not another attract user! Damn you, Whitney!
As Pokemon FireRed and LeafGreen told us, many awesome additions were made to help the current generation of Trainers out and make things feel much more familiar with their surroundings. Many Pokemon gamers were born after the release of the original Gold and Silver. So Game Freak helped out and added many new current generation features. No spoilers, but many legendary Pokemon, both old and new, were added to the games. This can help the new generation feel right at home.
You can't talk about HeartGold and SoulSilver without mentioning the PokeWalker. It's a pedometer that comes boxed with either version of the game. What you can do is send a Pokemon from your game to it, which it will gain experience and level up. But that's not all. You can also use a Dowsing Machine to find items and catch wild Pokemon on the small device. These items and Pokemon can be transfered to your game and used in them. Pretty handy if you don't have much time to train your Pokemon the old fashioned way. Another small adition is that you can now have the first Pokemon in your party tag along beside you instead of inside the confines of a Poke Ball. This also helps if you're training a Pokemon to be more friendly and boost the strength of the move Return. What's better than that, Pikaby?
Now what would happen if Chikorita was a Wailord?
As much as I love this game, there is one small problem. Some of the audio in the game isn't all that great. While the Dark Cave and Route 38/39 are great for music, the original tinny music sounded much better if you ask me. There is a way to remedy this situation, however. Spoilers involved, so I can't say it. But it has to do with a Gameboy...
As far as Pokemon games go, including the recent Mystery Dungeon games, this is by far one of the greatest Pokemon games anyone can buy. I can't help but love every second of this game. It will keep you up long through the night with a flashlight under your covers (wait, the DS has a backlight...).
Overall score: 9.5/10
Go and buy this game. I only kept it from being a perfect 10 because of some small audion issues.