Late to the One Game a Month Party

In my usual lack of style, I'm far behind the bandwagon on this One Game a Month business.  The basic premise is what is says on the tin, produce one complete playable game per calendar month.

So the crowning glory of this is to do the "12 in 12", one game a month for one year, or the perhaps less catch OGAMFOY.  As I'm slow on the uptake and missed the first month I can only do a OGAMFEM, which I actually like  the sound of a little better.

I'll throw my hat into the ring, lay down the gauntlet, and do whatever other kind of thing it is that people do when they start a challenge.

So how do we do this?  I imagine we start with an extremely simple concept, a good definition of done, and just sling code at it until it is playable.  Maybe make sure there's a basic gameplay loop, and just refine that until it is fun.  Make a second loop to tie together some progression of some kind, be it levels or waves or puzzles.  Then get it some title screens and end state.

Anyone out there participate in One Game a Month?  Any have any advice on how to get the Twelver?