Hi. . .
If you go to the actual location of Launcher.exe on the other drive (I assume it is NOT on your c: drive...?) and double-click on it, does the game start-up?
My only other thoughts on this at this time is that there may be some hard-coding in the game's source code that requires the entire program installation to be on your c: drive, which obviously is not a good coding practice if true because of situations just like yours. In general, you should be able to install any program on the drive of your choice.
Is there something else (other files) on drive c: that you could move to the other drive (s) to make room for the game on drive c: ?
One option to free up space on drive c: is to reduce the amount of space being used by Windows System Restore -
There is one other space reducing measure that comes to mind that will delete outdated/unnecessary (no longer needed) pre-Windows 7 SP1 related files on drive c: (assuming that drive c: is your OS drive) -- The "Disk Cleanup Wizard" - which a Windows legacy executable -
If you do run the Disk Cleanup Wizard, be sure to create a Windows System Restore point first - http://www.sysnative.com/forums/windows-7-windows-vista-tutorials/10909-windows-system-restore-create-restore-point-windows-10-8-1-8-7-vista.html
Did you try to create a new Desktop shortcut for the game's Launcher.exe file? Or is there no point in doing so because Launcher.exe simply will not run?
Regards. . .
p.s. Contacting the game developers is certainly an option here, but I doubt they would be much help in all honesty. They would likely just tell you to install it on drive c: -- period.
I myself rarely ever solely advise members to do so; I always try and provide some kind of alternative(s).
After all, you took the time to post your question here and the least we can do is try and help you install the game as you wish to do so.
Edited by jcgriff2, 12 August 2015 - 04:46 PM.