Can you think of a thematic idea of when one card is placed to overlap another? I have in mind of placing one card on top of another forming a cross shape wih the new card on top changing the landscape of the card underneath it, e.g., gravel on lower card and a paved road when the new card is placed on it. One game that sort of does this is Vom Kap bis Kairo:
http://www.boardgamegeek.com/boardgame/2555/vom-kap-bis-kairo
Thanks in advance as always.
Nice web artwork!