I defitnitely know this game and Crystal are my favorite Pokemon games for Gameboy. It is similar to Red/Blue/Yellowbut has new things such as new Pokemon, some new items, berries, and a new world-Johto. In thisgame you have to collect eight badges, beat the Pokemon League, and catch every Pokemon. Well now you get badges in a new region, Johto, and after you beat the Pokemon League you can go back to the same region that was in Red/Blue/Yellow, Kanto, and get the badges there. You have to catch 251 pokemon in this game, including the Pokemon from the older games. Team Rocket is also in this game causing more trouble. There is now berries and Pokemon can hold these and other items. There are different berries that heal energy and cure conditions like Poison and Burn. In Red/Blue/Yellow you could do things outside of battle with your Pokemon such as surfing in the water and moving bouldes, well now you can go up waterfalls and use a TM called Rock Smash to break rocks and get them out of your way. You can visit Kanto, the region from the last games, and there are some changes. If you loved Red/Blue/Yellow you will defitnitely love this game, maybe more.