I wrote my own init system in C from scratch some 13 years ago. It was more work than anticipated by myself and the manager who approved it. It served the purpose to bring up a Linux GUI and some backend for it on not so capable hardware in n seconds (don't remember n, but it was impressive).

It was a nice programming exercise. Wouldn't be suprised if even back then something like that already existed and the whole effort just demonstrated a lack of insight of what is readily available.

Probably the code still exists on some backup I should not have. Have not looked back and don't know... The company who owned the rights has gone out of business.

Edit: After typing this it came to my mind a colleague of mine wrote yet another init in the same company. Mine had no dependencies except libc and not many features. The new one was built around libevent, probably a bit more advanced.