I purchased this game from Walmart & when I tried to install the game all I get is "Unable to install" with no additional information. Paradox Interactive should not be selling defective software. I tried to contact thier Tech Support & they refused to help. Paradox Interactive has poor customer service & tech support. They are very unprofessional. I recommend that everyone save their money and dont buy anything from Paradox Interactive.
If you're having problems installing the game, simply go to Paradox's forum, register your game (if you don't register your game you won't be able either see or post in their tech support forum), and ask for help in Rome's tech support forum. Both the mods & users at the Paradox forums are usually very helpful, so you'll definitely be able to find help there.