I was just thinking about Opa the other day - it looked nice but I never used it. People were worried about debugging through the layers of abstraction. Is it still "alive"? You write in the past tense...
Many things we did became hype later (implemented in OCaml, a functional language, JSX before React - I know Jordan played with Opa before building React) and we still have bits that are missing is today's stacks. The ideal next step would be to join a foundation so that development on the project could resume.
I was always very disappointed by the fact that the inner workings of Opa were never described in any way. I can't even really cite it in my PHD thesis, because the documentation for the early (and more interesting, imho) versions has completely disappeared.