org-stuck-projects

org-stuck-projects is a variable defined in `org-agenda.el'.
Its value is

("+LEVEL=2/-DONE" ("TODO" "NEXT" "NEXTACTION") nil "")

Documentation:
How to identify stuck projects.
This is a list of four items:
1. A tags/todo/property matcher string that is used to identify a project.
See the manual for a description of tag and property searches.
The entire tree below a headline matched by this is considered one project.
2. A list of TODO keywords identifying non-stuck projects.
If the project subtree contains any headline with one of these todo
keywords, the project is considered to be not stuck. If you specify
"*" as a keyword, any TODO keyword will mark the project unstuck.
3. A list of tags identifying non-stuck projects.
If the project subtree contains any headline with one of these tags,
the project is considered to be not stuck. If you specify "*" as
a tag, any tag will mark the project unstuck. Note that this is about
the explicit presence of a tag somewhere in the subtree, inherited
tags do not count here. If inherited tags make a project not stuck,
use "-TAG" in the tags part of the matcher under (1.) above.
4. An arbitrary regular expression matching non-stuck projects.

If the project turns out to be not stuck, search continues also in the
subtree to see if any of the subtasks have project status.

See also the variable `org-tags-match-list-sublevels' which applies
to projects matched by this search as well.

After defining this variable, you may use M-x org-agenda-list-stuck-projects
or `C-c a #' to produce the list.

You can customize this variable.