Possible Duplicate:
2nd Steam Account on the same Computer?
They use the same computer that I do, but they use different Steam and computer accounts. I have already downloaded and installed the game on my account and my brothers want to play it on theirs. Do they have to redownload or reinstall the game? It is already installed on the computer. If there is a way for them to play the game without needing another 20GB, please EXPLAIN it because I searched a lot and no one specified different COMPUTER acounts, only different Steam accounts on the same computer account, which is not my case. I'm using Mac OSX 10.6.8.