Just tried this on Windows 10 Pro (latest insider preview build), if you want to make the change on the client.exe instead of the nclauncher:
Open Regedit:
1. Navigate to [HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\AppCompatFlags\Layers].
2. Create a new String Value in the right pane, and name it with the full path of the program’s exe file. By default that would be C:\Program Files (x86)\NCSOFT\BnS\bin64\Client.exe (no " needed)
3. Set the value to the following:
~ WINXPSP3 works best for Windows 10 Pro 64bit (makes no sense but works!)
~ WIN7RTM for Windows 8/8.1(apparently from reading above)