Apart from GSD and superpowers, there's another system, called PAUL [1]. It apparently requires fewer tokens compared to GSD, as it does not use subagents, but keeps all in one session. A detailed comparison with GSD is part of the repo [2].

[1] https://github.com/ChristopherKahler/paul

[2] https://github.com/ChristopherKahler/paul/blob/main/PAUL-VS-...