I just bought a copy of CoD Modern Warfare from Walmart. How do I install it when I don't have an optical drive? Can I image it on to a USB drive? Since it uses steam could I install it on another computer and then now that steam has it verified download it on to my main computer through steam? Do I need to borrow an external optical drive from a friend?
Under the GAMES tab of steam, select ACTIVATE A PRODUCT and enter the Key you got in the game case - then download and install.
or if you want to have some fun with it, you could use a second computer to rip the image with imgburn then move it via usb to the pc you wish to instal it on and then mount the image with something like poweriso.