THANKS TO TPG!
OK HERE IS THE SOLUTION, i wrote it down for beginners:
1) Copy the file "OpenTransport", that you can find it in the folder "/System/Library/PrivateFrameWork/OpenTransport.framework/Versions/A/", of a previous OS X version (e.g. Lion, Mountain Lion) into "Zero Hour.app/contents/MacOs/".
2) Rename the file "Zero Hour" that you find in "Zero Hour.app/contents/MacOs/" in "Zero Hour_bin"
3) Open TexEdit, create a new txt-File, copy this Code in it and save it as "Zero Hour" (no file extension)
#!/usr/bin/env python
def main():
import os
path = os.path.dirname(os.path.realpath(__file__))
command='DYLD_FORCE_FLAT_NAMESPACE=1 DYLD_INSERT_LIBRARIES="{0}/OpenTransport" "{0}/Zero Hour_bin"'.format(path)
import subprocess
subprocess.call(command, shell=True)
if __name__ == '__main__':
main()
4) Make the file "Zero Hour" you just saved an executable by going to terminal and typing "chmod +x Zero\ Hour)"
5) Copy the executable file "Zero Hour" into "Zero Hour.app/contents/MacOs/"
6) Now just double-click on the file "Zero Hour.app" an the game starts.
Thanks again to TPG!