I've just completed a small D/GtkD game.
It might be useful for others trying to learn GtkD since it is only just over 1000 lines, yet shows how to create a dialog-style app with a modal dialog and a modeless dialog, and a custom drawn widget, as well as keyboard and mouse handling.
The source (and a 64-bit Windows binary) is here:
Any advice/feedback from D and GtkD experts to improve the code would be of interest.
(I also posted similarly to this on the D Learn forum since I'm not sure if people read both.)