Need Help with Creating a Board Game

So, I want to come up with a game to be played at Dag events.

Board should be simple enough to draw on a piece of leather that can be rolled up, pieces can be anything, but I happen to have some 3/4" wooden blocks to use.

I'm pretty new to developing things like this, so I was wondering if anyone has any direction for coming up with initial objectives and gameplay mechanics to start playtesting?

I'm looking to make something with a movement and capture element, possibly some chance, but not an overwhelming amount, and some variety in unit abilities.