Initiative.sh is a storytelling tool for game masters who live at the command line. You define and describe the world to it, and it then responds to your queries, keeping track of location, context and other important cues. It's a kind of digital text-based equivalent to dice, DM books and the stack of worldbuilding documentation that grows around one's campaigns, with built-in item/NPC/place generators and other Donjon-esque storytelling aids. It feels almost like a computer game itself, somewhere between open-world and editor, a textmode God game. It's built around the D&D ruleset, but has obviously broad potential for adaption to (and beyond) other role-playing systems.
Creator Mikkel Paulson, writing at Hacker News:
I've barely scratched the surface of the feature that I'm most excited by, namely context. Soon it will be possible to tell the app where the party is and what they're doing, and the demographics of suggestions (and ultimately music, lighting, and other integrations) will be updated accordingly. In a seedy bar in the docks district? You're more likely to run into sailors down on their luck. Pick a fight? Cue the epic music. Sun sets? Dim the lights.
More details are available on my blog: https://mikkel.ca/blog/introducing-initiative-sh/