I have been working on this as a hobby project for a few weeks now, and it's starting to look decent. It is barely an early alpha yet, so please forgive any catastrophic data loss etc...
It is a tool for breaking down projects into manageable pieces, and to estimate the total time of the project. Pretty useful. I've been dogfooding during the development, and it is a lot better than my usual method of indented lists in a text file.
* Click the button to create a new project.
* Type in your project title.
* Click the "+"-button to add a task.
* Hover over a taks to see the button for adding subtasks.
* Drag&drop task to reorder them or move them up/down the hierarchy.
* Open the edit-dialog on a task to set an estimated time.
* When you enter the first estimate in a task, you get projected estimates for all other tasks.
It is desktop-only at the moment. Some of the stuff works on mobile, but don't count on it. None of the drag&drop works, for example, and it relies on mouse hover.