Hi,
Here is an idea I did not try, but maybe someone else did. (let me know if this is what some of you have meant by the tree of chambers idea...)
If you and the opponent are separated by one or more articulation points, use dynamic programming to determine if the position is a win, and whether it is better to fill the space you are in, or run to cut off the other bot at a cut point. Alpha-beta / voronoi will find this if the moves are close enough, but maybe this idea could extend the look-ahead of these algorithms.
This might only help some of the weak spots in my evaluation function, and I ran out of time (and energy), so it did not happen.
Thanks,
Dave