A number of years ago I identified for myself what I needed to be able to do to write the games I wanted to (Isometric RTS and RPG games).

Based on this list I narrowed my focus to the point where all I tried to learn about game dev was those items Identified (e.g. No 3D stuff, Only 2D, some networking, Joystick input etc).

I am currently very happy with where my skills are. I can now write the games I want to be able to write (Run-A-War was a major accomplishment for me ). There are still things I need to learn - the most important of which is Modelling to make the sprites for my games.

There are some things that I dont feel I do that well :
:arrow: My mathematic skill is far too low for what I need.
:arrow: I dont know enough about AI - I only really understand fuzzy logic based rule systems.
:arrow: My modelling skill doesn't exist.
:arrow: My discipline is lacking - I havn't worked on any games for a week now, my last backup was a month ago etc.