Hi!
I noticed that if Visual Studio is installed in a non-standard location (program files (x86)) then unreal engine has problems finding cl.exe which causes it to fail on project file generation.
I noticed that during the installation of VS, it installs cl.exe under program files (x86) but devenv and other editor-binaries are in your custom directory.
Are there system variables available to provide unreal engine with the correct path to cl.exe?
I did a full reinstall of VS2013 community edition under program files (x86) to confirm that it works and that this was the actual issue at hand.