In the iPhone version of Warfare Incorporated, testers were geographically somewhere else which made this problem even more fun. A history of the state on each client that led up to the divergence is needed to find these problems. When hashing game state, WI clients maintain a log of the state contributing to the hash at a useful level of detail. The log gets trimmed as the server acknowledges hash matches. On hash mismatch, clients post this log to a server for analysis.