It was installed/aborted on my main account but the shortcut from first install is on the sub account. The only way I can see that happening would be if the installer created a shortcut across accounts, which it shouldn't do by default. (I think) Either way though, wouldn't it still have been installing into the wrong directory at that point, since it generated a D:\Games\launcher.exe link in the process? Or at the very least, the installer/launcher updated the shortcut to this incorrect info at some point in the process, right?
I wonder if there isn't a $path issue or something confused in the registry because I finally clicked that wrong shortcut and it didn't error. It just ran launcher.exe as if it was actually in the location then changed that shortcut to the new location. Might have just been windows auto-magic, but I seem to remember there being a prompt in those circumstances of a broken shortcut. I dunno, just a guess. (Both could very well be messed up from my dev work and this old install of windows.)
Sorry for the trouble, and thanks for the time.