@ludwa6 Good question. This is my experience: I learned about GTD probably 17 years ago. I seemed an excellent time/task management at that time. Several Windows applications were released, and I tried at least three of them. I am not sure though I think copyright/trademark issues prevented further development of those applications, which weren’t great in any case. By early 2010 I discovered TW Classic. In the next two/three years several “GTD” based TWC applications appeared in the scene. Besides mGSD by Simon Baird, there were tbGTD by Tobias Beer (http://tbgtd.tiddlyspot.com) and d-cubed by Tom Otvos (Welcome to d-cubed). All three TWCs took some ideas of GTD (based on GTD) though didn’t “mirror” GTD. After reviewing the three, liked mGSD the most, and used it from 2013 to early 2022.
Regarding GSD5 by Roma Hicks (https://gsd5.tiddlyspot.com/), Cardo by David Szego (Cardo — A TiddlyWiki for Getting Stuff Done Click to Get Cardo), and Projectify by Nicolas Petton (https://projectify-demo.tiddlyhost.com/) in TW5, they are similar applications, with a different flavour. Projectify is not based on GTD but on Todoist and Basecamp.
I am using GSD5 now, though my ultimate goal would be to have a new more robust application like mGSD, maybe with a totally different name.
I believe mirroring the GTD system in TW5 would be relatively easy, if that is what you want (it’d be a “watered down” mGSD though). Several TW5 programers here could write a plugin for a fair price in less than a month.The issue here would be how to circumvent David Allen’s copyright/trademark.