Clearly, software projects are different from other industries in terms of many things like for instance, quality assurance, project progress measurement, and many other things.

Unique characteristics of software projects also makes the risk management process unique. Lots of issues in a project might lead it to unacceptable delay or failure to deliver business value. They might even make a complete disaster in the project.

What are the deadliest risk factors in a software project? How to analyze, prevent and handle them? Particularly, I'm interested in the issues that you can detect from the beginning and you should keep an eye on (for example, you might be told about a third-party API that the current application uses and lacks documentation).

Please share your experiences if they are relevant.