Assume failure then figure out how it happend. This is a method of risk identification.

Game development is a risky endeavor: It is a good idea to track the biggest risks, develop a mitigation plan, and create contingencies in case things go wrong. But risks aren’t always obvious. One way to help identify risks is to write a pre-mortem. I’m sure you’ve read game development post-mortems before. If you haven’t you need to, immediately! The idea behind a pre-mortem is to assume failure and imagine the various ways that could happen. Have everyone on your team go through this process to get more resolution on potential problem areas.

Borderlands 2