OK, today my rant - copy protection mechanisms used on game CDs and DVDs which mean that you have to have the game in the CD/DVD drive in order to be able to play it.

I did originally have Disc 1 on my USB, but did not try installing the Play Disc to HDD. I did a complete re-install of Disc 1 to the HDD instead, then installed the Play Disc to my USB.

Want to bulk or batch install multiple games at once in Steam on PC? See this post for the step-by-step instructions you need to follow.

It looks like Konami has shipped retail PC DVD-ROMs of MGSV with only a single 8.8MB installer file, meaning you still have to download the full 20GB+ game via Steam.

Call of Duty: Modern Warfare 2's game disc has 72 MB of data on it, though the game itself is 100 GB to install.

Remember when Rockstar said not to install the game disc? Turns out there's a workaround if you've got a big USB drive.