The game is basically about capturing pokemons, and there are 4 types of pokemons: normal, ghostly, dark, metallic and shiny. Which means you can have ( as an example ) a regular normal pidgey and a ghostly pidgey, but all the non-normal pokemons are much rarer than the normal.
It's also possible to battle against gyms from Kanto, Jhoto and Hoenn and the leagues. When you have all the badges, the legendary pokemons will appear.
Example:
Dark Mantine -
![Image](http://static.pokemoncrater.com/pokemon/Dark%20Mantine.gif)
Shiny Mantine -
![Image](http://static.pokemoncrater.com/pokemon/Shiny%20Mantine.gif)
Of course, the game has a trade system where you can trade your pokemons for anyone else pokemons and the forums are not that bad either. It can look boring at first because you have to move your character around the maps using a system similar to the one found on neoquest ( neopets ), but it's really fun and addicting once you get used to it.
![Very Happy :D](./images/smilies/icon_biggrin.gif)
My username there is Crucialus. ^____^