Remix was odd; I remember having a 'ghost' installation of FF7 on my machine that would only appear when running the executable as admin. Never figured out what was going on in there, but it all got wiped when I updated processors and needed to clear the HDD.
It was probably installed in Program Files. Windows Vista and on do this really stupid thing where, to protect files in those folders, they make essentially ghost versions. This is called VirtualStore
There are some advantages:
- It allows each user to have their own versions of settings and documents that go with a program, even if it assumes all these files go in its own folder.
- It significantly reduces the likelihood of accidental modification of something in Program Files, which can cause applications to break.
- It inhibits the ability of trojans to screw around with your software.
Further, this only applies to 32-bit applications, and only when they're not run as admin. It's pretty much there as a workaround to help older, pre-Vista software work correctly.
Unfortunately, when you actually WANT to tweak game files, such as with game modding, it can really get in the way, by causing changes to appear not to stick, by causing tools to work with a different version of a file than the game is using, etc. This is one of the biggest reasons it's not recommended to install FF7 in Program Files or any other "system" folders if you intend to mod it.