Stones.

The wife and I went to the beach this afternoon, and found a profundity of very smooth basalt stones.  She mentioned that ‘these would make great game pieces’, so of course I scoured the beach for a couple of handfuls.  The result:

Twenty-five stones in all of various sizes: twenty-one drak gray, and four white ones.  The mechanic: reach into the bag and draw out the stones for a conflict.  Grab as many as you want, but if you draw a white one (or more than one), you fail.

I’m also thinking about the arrangement above: the stones are laid out in a 5×5 grid, with the final pattern being significant in some way.

Now the question is: what’s the theme?  What sort of game would call for this as a mechanic?