are the altered versions more fun r even worth buying?
They are all free but it requires you to have the ROM of the required game (ie:Firered) in order to patch it to create the Hacked game. In order to use ROMs you have to own the game first, otherwise it's illegal.
some of them put viruses on ur computer. not fun.
That's why you have to be careful about what you download from the net. The ones on PokeCommunity are perfectly safe because you have tons of people that comment and if one has a Virus they get banned.