PIGen is a PI System test data generator for teams who need a believable plant before the real one exists. It backfills years of history into the PI Data Archive, streams live values in real time, and replays causally linked upsets - so demo displays move like a running plant, training scenarios reproduce real events, and new PI Vision dashboards can be validated before a single field tag is wired. Unlike a random-walk simulator, every value comes from a causal engine: trip a pump and flow, pressure and vibration follow it down together. Creates the PI points it needs and writes straight into the historian, comfortably sustaining about 870 tag writes per second on a single node. Windows desktop application, annual licence.