There's a thread on the forum about this, but there's a problem it didn't address that may creep up more as people start using 8, and I thought I'd make a separate thread that's more comprehensive about it.
Omerta and its crack are compatible with Windows 8. This much is fact. Getting it to run, on the other hand, may pose a problem even if you follow all the instructions. You know it happens when alsignuptool says it's got the wrong version, or if no matter how many .sig you make and rename, the game still asks for a copy protection file.
This happens, I've found, if you have another game using recent versions of AlphaRom on the same computer. When this is the case, another version of Alphadisclog.txt (the file that allows alsignup to read the code needed to generate the fake .sig file) for the other game will be where Omerta's should be (My Documents\SETTEC and sometimes C:\), and Omerta can sometimes NOT overwrite the file, instead throwing it elsewhere in the computer that's not entirely obvious. So when you run alsignup, it's looking at the Alphadisclog.txt for the OTHER game instead, because it's the one in the right directory.
You'll have to find the right file for Omerta.
Run a search in C: for Alphadisclog.txt and find the one that's created at the time you installed Omerta. You'll know it's the right one if the error_code section in the file is 1503. Mine was in Users\[username]\Appdata\Local\Virtualstore
Rename your old Alphadisclog.txt in My Documents\SETTEC to something else, and copy Omerta's alphadisclog there. Go back to your game directory, run alsignup, goto ProgramData\Asign and get your .sig to rename to alsign.sig, generate another .sig, copy alsign.sig to Omerta directory.
Or in bullet points, do this if Omerta won't work even if you followed all the other directions here and you use W8.
1. Clean install Omerta. Note the time. Run once until error appears.
2. Run a search in your C: for an Alphadisclog.txt. Find the one that's created right when you installed Omerta.
3. Wherever the file is, copy it to My Documents\SETTEC. Rename older files if necessary.
4. Copy alsignup tool to Omerta directory. Run once.
5. Go to ProgramData\Asign (ProgramData is a hidden directory), sort on date, and rename the newest .sig to alsign.sig
6. Run alsignup tool for Omerta again
7. Cut and paste the alsign.sig to Omerta directory
8. Run the game.