Sadly too many pc games have bugs which are not apparent at the time of release; often the larger manufacturers release patches for download, but for budget games this is rare, and as you say, no use to someone without internet access.
The problem comes when you try to get a refund or exchange for a different game. Most retailers don't want to know once you've opened the packaging, because of software piracy.
Anyway, have you found and downloaded the required codec and got it working??