Unzip the .rar using an unzipping program like 7zip or Winrar, open the folder then launch the application.
are any of them free?
I believe they're both free. I know Winrar will say you're using a trial version when you first boot it up, but you can ignore the message and continue using it for free forever.
does it require a powerful computer?
My games usually run well on decent computers, I'd say.
