Fun story. I remember meeting Tyler Renelle way back at a JS meetup when he first started developing it. Not 100% sure, but I think he originally built it off a framework called SocketStream[1], though I don't remember exactly (I was a contributor to SocketStream at the time). It might have actually been another of the similar frameworks[2] at the time that relied on sockets, realtime-app predecessors to React/Angular/Vue/Svelte.

I used Habitica early on, and it was fairly fun, but I could never (irony much) keep the habit of using it.

Update: looks like it was Derby: https://github.com/HabitRPG/habitica/search?o=desc&q=derby&s...

[1] https://github.com/socketstream/socketstream [2] The competitors were Derby https://derbyjs.com/ and...can't remember the other one off the top of my head.