Semantic Synchrony is an open-source (free) knowledge graph editor. A knowledge graph is what lets Google, Siri, WolframAlpha, probably the CIA, and others answer questions about the world. However, unlike those systems, Semantic Synchrony is easy to use -- much easier than Microsoft Word or Minecraft -- and more general.
If that seems unlikely, there is a simple economic explanation: Systems like Google's are optimized for computer reasoning, whereas Semantic Synchrony is optimized for human reasoning. Currently, computers can only reason on a graph that adheres to some fixed schema, which limits what can be expressed, and how. Semantic Synchrony imposes no such limitation; knowledge in the graph is just text, written however you like.