12.21.11 The by now famous Best of ChessMaine.net end of the year review will be coming to a computer screen near you soon. While our legions of bean counters pore over reams of statistical data separating the wheat from the chaff, we encourage you to take a crack at this composed problem of retrograde analysis. If it's too easy, don't despair, we've got plenty more of the fiendishly maddening variety.

What was White's last move?