What's your operating system, and are there any errors? If you're on Windows, SmartScreen or some other virus-protection program might be blocking it, in which case I'd recommend unblocking metro.exe in said anti-virus program.
I don't have any antivirus, besides the program freezes upon launch; implying something maybe wrong with the exe file itself.
Hard to say what's wrong with the game on your system based on this, sorry.
